Hello friends, welcome to Unacademy. Let's crack neat PG. I'm Dr. Shonali Chandra and in today's session we will be discussing the important physiological changes in pregnancy and their clinical implications. This is going to be the first part of the session. I will take up the second part of the session tomorrow.
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There's a capsule course on high-risk pregnancy, gyne-oncology, clinical situations in early pregnancy, labor and its complications, as well as on reproductive gynecology. So you can check out these PLUS courses on the platform as well. But coming back to the session at hand for today, we're going to discuss the physiological changes in pregnancy.
Today, I'm going to be taking in the first part of the session because the second part will come tomorrow. I'll be discussing the various reproductive tract changes and I will be discussing the various metabolic changes which take place during pregnancy, right? So let's see who's joined in here. So we have Osborne here, Nirmal, Peter. Good evening to all three of you guys.
So let's get started without wasting any further time and talk about changes in the reproductive tract. tract. Now, the one thing that is very pertinent and very obvious change in the reproductive tract is the growth of the pregnant uterus.
Now, how much does the uterus weigh in pregnancy? Well, obviously, it will keep increasing in weight in pregnancy because of, yes, there's a fetus growing inside the uterus. But other than that, also, there is the growth of the uterus's muscle as well.
So, yes, the pregnant uterus at term weighs about 1100 grams. So from being 50 to 70 grams in the non-pregnant state, a pregnant uterus at term weighs about 1100 grams. That's the weight of the uterus alone.
And that somewhere correlates to about 5 liters of capacity of the uterus as well. Now, what is responsible for this growth of the pregnant uterus? What is responsible is myomatrial hypertrophy as well as hyperplasia. So both of the things occur and it is a direct estrogen related change. It is a direct estrogen related change.
Estrogen is responsible for causing myomatrial hypertrophy and hyperplasia. Now, the other question that they ask you in your exams is what is more predominant? Is hypertrophy more predominant or is hyperplasia more predominant?
What occurs more hypertrophy or hyperplasia? So hypertrophy is a more predominant change as compared to hyperplasia. That is another important point to remember for your exams.
Now, the next important thing is that this hypertrophy and hyperplasia is mainly limited. to the first 12 weeks of pregnancy. All of this hypertrophy, hypoplasia is predominantly taking place in the first 12 weeks of pregnancy.
So what happens after 12 weeks? So thereafter, further growth of the pregnant uterus is occurring because of stretching of the myometrial fibers. You see there's a fetus growing inside so that is causing stretch to the myometrium.
And that is responsible for further growth. Now, the next question that arises is that what happens after delivery of the baby? After delivery of the baby and during the postpartum period, during the puperal period, the uterus is going to come back to its non-pregnant state, isn't it?
So when it comes back to its non-pregnant state, does it come back to being 70 grams? Does it come back to being 70 grams? Can it? Because there has been hyperplasia that took place. place during pregnancy.
So even after delivery, mind you, even after delivery, mind you, and approximately about four weeks after delivery, the weight of the uterus never comes back to being 70 grams or what it was before pregnancy. It's somewhere around 100 grams. It's somewhere around 100 grams, right?
And with each subsequent pregnancy, there will always be some residual weight. in the uterus. So you must have seen many ultrasound reports of multiparous women and you know they always say the uterus is bulky slightly larger than what is in the nulliparous state right.
So that is the reason for this that pregnancy is associated with hypertrophy and hyperplasia of the muscles. Now another important thing to note about this growth of pregnant uterus is if you look at it in a little bit of more detail Then the growth of the uterus when it happens, especially the myometrial growth when it happens, you see, the myometrial fibers, they are arranged in three distinct layers, right? So there is an outer longitudinal layer, okay?
Outer longitudinal layer. There is this inner circular layer as well. Inner circular layer as well, right? And that is around this area. That is the area of the cornu and the area of the isthmus.
as well. So there's an inner circular layer and then there is a middle layer of the myometrium which is the most predominant layer. This is the thickest layer. This is the thickest layer.
This is the most predominant layer and indeed this is the most important layer as well. So let us see how this becomes the most important layer or why so. So yes if you have to understand the clinical implication of this growth that, you know, the middle layer is the one which is the thickest. So yes, often they ask you in exams that what is the main mechanism of controlling blood loss after delivery? What is the main mechanism of controlling blood loss after delivery?
So the answer lies in the arrangement, typical arrangement of muscle fibers in the middle layer of the myometrium. So in the middle layer, the myofibrils are arranged in a crisscross pattern with the blood vessels. running between them. So it is when these myometrial fibrils they are going to contract because that is how the uterus is going to contract the blood vessels are going to get constricted and they're going to stop the bleeding after delivery. So the main mechanism of controlling blood loss after delivery becomes the uterine contractions indeed yes so the middle layer of the myometrium is what is called as the living ligages, very rightly told by Peter here.
Right. And another important implication of this is that what is the main cause of postpartum hemorrhage then? What is the main cause of postpartum hemorrhage then?
What is the main cause of bleeding soon after delivery? Well, for any reason, if the uterus fails to contract and remains atonic, that becomes your main and most common and the most important cause of postpartum hemorrhage. as well the clinical implication lying in the arrangement of the myofibrils in the middle layer of the myometrium all right now let's talk about the clinical implication of growth of the uterus further right so as you can see on the diagram here you see as and when the uterus so if this is the pelvic inlet here so you can see here that the uterus initially is going to be small and then it is going to become further bigger and then further bigger and then further larger and then further larger.
So when is the time when the uterus becomes an intra-abdominal organ or when is the time when the uterus starts becoming palpable per abdomen or when does it come outside that of the pelvis? So that is another important MCQ that they ask in your exams. When does uterus start? come out of the pelvis. Yes, when does that happen?
It happens around 12 weeks of gestation, right? So uterus extends out of the pelvis by the end of 12 weeks of gestation. Thereafter, it becomes an abdominal organ and it keeps increasing in size further and further, right?
Now what is important to note here is that when this uterus extends as and when it increases in size you see there are the round ligaments round ligaments from the sides of the uterus right at the corneum and they are traveling to the uh external uh uh sorry they're traveling to the lateral pelvic wall from there they're traveling to the um deep inguinal ring they're in the inguinal canal and then They get attached to the labia majora after coming out from the superficial inguinal ring. So if you trace the path of the round ligament, this is the round ligament and it gets stretched. It is attached here somewhere to the anterior part of the labia majora after it has traveled in the groin.
So as and when the uterus enlarges in the second trimester, you see there is stretching of the round ligament and this stretching of the round ligament often leads to pain which is you know radiating towards the groin area of the woman she will complain as if somebody is lifting her uterus she'll feel it at the perineum she'll feel it at the region of the groin so what is this pain called as which is occurring because of the stretching of the round ligaments it is called as the round ligament pain and this round ligament pain is a sharp pain, you know, sharp stabbing kind of a twisting kind of a pain which happens near the groin. And it is unilateral usually, but can be bilateral, right? And it is felt in the second trimester onwards, particularly, and it is often worsened by sudden movement. So if you take the history of the woman further, she'll be able to tell you that, you know, whenever she suddenly gets up from bed, or suddenly changes her posture, or she's been sitting in a certain position for a certain time and then suddenly moves you know so sudden jerky movements they worsen this pain now as far as the treatment of this round ligament pain is concerned you need to counsel the woman that what she's experiencing is something which is particularly you know typically physiological and normal and she didn't she did not worry about this pain it can get relieved by you know local heat application and Anti-spasmodic treatment is seldom required because you know it is not a continuous pain, it happens sometimes and you know you can ask her to avoid jerky movements and you get up from the bed slowly or change her posture slowly. So these kind of arrangements can help her with this kind of pain that is the round ligament pain.
Now moving on further, the further clinical implication of the growth of the uterus here is that as and when the uterus you know comes out of the pelvis becomes an intra-abdominal organ, grows bigger and bigger, there are tendency for other uterus to become dextrorotated, isn't it? There's a tendency for the uterus to become dextrorotated because the left side of the pelvis is filled up with the rectosigmoid. So the uterus slightly tilts towards the right side.
And you can see here that in lying down position, what happens is that the uterus falls over these vessels which are there in the abdomen, right? So the uterus will fall over these vessels. I mean, I've drawn them with the red color, but I should be actually drawing it the vein actually, because the vein is on the right side there. So it compresses or puts pressure on the great vessels and particularly the inferior vena cava, which is on the right side.
And then a woman often complains of what? I mean, she's lying down for a long duration of time and then she suddenly gets up from bed. And if she suddenly gets up from bed and then, you know, she stands up upright, it can lead to a sudden drop in blood pressure because, you know, All this while the uterus has been compressing the inferior vena cava.
So there is a peripheral pooling of blood because of the venous compression, right? So there is venous compression. There is peripheral pooling of blood. And there is, as a consequence of that, there is a decreased venous return as well.
So when a woman suddenly gets up, she can have that episode of, you know, slightly lightheadedness and dizziness, what we call as the soup. supine hypotension syndrome yes so she can aisha very rightly said she can have hypotension right so supine hypotension syndrome is particularly problematic in pregnant women but they need to be counseled yes of course that you know they should get up from the bed slowly so if they're lying down they need to shift from lying down position to the left lateral position first stay there in the left lateral position then slowly get up from bed sit for a while and then stand up right so so they have to get adjusted to this as well. So yes, of course, like I said that the left lateral position is the best position in pregnancy to be in, isn't it?
So particularly as and when the uterus is large enough in the late second trimester, the third trimester to compress the inferior vena cava. So lateral position, left lateral position is the preferred position because then it lifts off the uterus from the inferior vena cava as well, lifts off the compression, right? And left lateral position is also particularly very good position because you see then the compression on the aorta is also lifted off right so aorta is the main branch isn't it it's the main branch of the artery there and it is the aorta which is giving rise to the ilac arteries the ilac artery which is supplying the uterine artery and the uterus person everything so all the blood supply to the uterus is maintained ultimately by the aorta only to begin with right So in the left lateral position, you see the placental perfusion is also better.
So that is another reason why left lateral position is preferred. There is increased placental perfusion because of increased uterine artery blood flow. So let's focus more on the uterine artery blood flow during pregnancy.
So I told you that the uterine artery flow in pregnancy needs to increase throughout pregnancy. So let's focus more on the uterine artery blood flow during pregnancy. You see from the non-pregnant state, you know, in the non-pregnant state, the blood flow into the uterine artery is only about 550 ml per minute.
And the blood flow at term in the uterine artery is about 10 times more. It's about 500 ml per minute. That is a lot of increase in uterine artery flow.
Now this increase in uterine artery, uterine arteries, let's say, let's demarcate the location here of the uterine arteries, blood flow is increased to the uterus as well. And blood flow is increased to the placenta as well. So for that reason, you know, there has to be increased uterine artery flow. Now if uterine artery blood flow is going to increase, you know, it will going to happen what has happened is that there will be uterine artery vasodilatation also.
right then only the uterine artery is going to allow for the increased blood flow so the uterine artery is dilated during pregnancy and there is also an increased velocity of blood flow in the uterine arteries and you see what is responsible for making the uterine artery dilated the pregnancy hormones your hormones like estrogen progesterone right so this Dilatation of vessels is under the control of estrogen, progesterone, locally released nitric oxide. These are what are contributing to the vascular dilatation downstream. Right.
So what is the clinical implication of this increase in uterine artery blood flow? So sometimes what you can do, sometimes what you can appreciate is, you know, as and when you put your stethoscope on the woman's abdomen, especially near the pelvis, near the sides of the uterus, you can sometimes hear, you know, a very whoosh whoosh kind of a sound and a very rapid it is. And, you know, like a clock and but it is not.
tick tick it is a very whoosh whoosh kind of a sound what is that called as what is that called as what is that called as what is that called as what is the clinical implication of this particular finding yes so that is called as the uterine swivel so sometimes you can hear that on you know ordinary auscultation with your ordinary stethoscope or sometimes with a handheld doppler also you can hear that sound but do not confuse it with a fetal heart sound. Do not confuse it with a fetal heart sound because this uterine sufl is going to coincide with the maternal pulse. It is going to coincide with the maternal pulse and it can be heard on the sides of the uterus lower down in the abdomen. Right? Now the other important thing to note here about this uterine sufl is that There can be many other instances apart from pregnancy where the uterine artery flow might be increased.
For example, there's a very vascular fibroid. So you can get this sound in other conditions as well. But yes, particularly in pregnancy, we often hear it. And then we don't have to confuse it with the fetal heart rate.
Okay, because fetal heart rate will be much more rapid, whereas your uterine suple is going to coincide with the maternal pulse. Right. Now, another thing that you can appreciate is sometimes in pregnancy, you see, and they ask you a question on this, that if I were to do a PV examination and if I were to put my finger here through the lateral vaginal fornix, I might be sometimes able to feel this uterine artery pulsating because it is dilated with an increased velocity of blood flow. Now, what is that sign called as that when you.
put your finger through the posterior vagina through the vaginal phondix lateral vaginal phondix and you might be able to feel a pulsating uterine artery what is that sign called as no that sign is not called as palmer's palmer sign is when you cup the uterus in both the hands during pv doing a bimanual per vaginal examination you are able to feel rhythmic uterine contractions that is palmer's sign This sign here is your Oceander sign. Oceander sign is when we feel the pulsations through the lateral vaginal fornix and it can be elicited at around eight weeks of gestation. It can be elicited at around eight weeks of gestation.
So that is also important to remember. Now, Amman, you're asking me a question that is way off, but let me just give that to you here also. Can I take that doubt in the end of the session? Aman, please remind me at the end about this question because it's off the topic.
I'll deal with it in the end. Now, what are the other changes in the cervix that you encounter? What are the cervical changes? So one of the cervical changes, again, because of the estrogen and progesterone hormones is hypertrophy and hyperplasia of the cervical glands, like we were discussing yesterday as well. So this Hypertrophy and hyperplasia of the endocervical glands can lead to pouting out of the endocervical epithelium onto the squamous layer.
So this is your ectocervix, right? And that's your bright red endocervix, right? So endocervical epithelium can pout out.
Now do not confuse this with an abnormal finding. This is what we call as cervical ectropion or ectopia also sometimes and it is absolutely physiological and normal, all right? Now other than that, there is a mucus plug that forms within the cervix.
So you have the cervix here, there is a hypertrophy and hyperplasia of the endocervical glands, right? So these endocervical glands are the ones which are secreting a lot of mucus, right? So what can happen is that there is a mucus plug here which forms.
And this is quite protective. You see, it nicely protects because it prevents the ascent of infections as well through the vagina upwards. And it is the same mucus plug, you know, which can get expelled once the woman enters labor and once the cervix starts to dilate.
So this cervical mucus plug can get expelled during the opening of the cervix during labor. And when that does happen, there is a slight blood also mixed with it. Slight blood also mixed with it.
Little bit of blood mixed with it. Now, what is this called as? This is what we recognize as show.
This is what we recognize as. show. So women who are going into labor can give this clinical history that you know they have some discharge, some mucoid discharge mixed with blood. Now that is the mucus plug that has been expelled and it has formed throughout the nine months of pregnancy, right?
Now, apart from that, there is also softening of the cervix, right? So the connective tissue of the cervix also undergoes changes, right? Cervix as compared to the body of the uterus is mainly connective tissue.
Now, the connective tissue of the cervix, again, you know, is elastin and collagen. So there is a lot of water retention in the cervix. There's some collagen breakdown that is taking place in the nine months of pregnancy, a little bit of this happening.
So there is softening of the cervix. which we can elicit on the pervaginal examination. So if you were to digitally feel the cervix of a non-pregnant woman, then it feels firm like the tip of the nose.
But if you were to digitally feel the cervix of a pregnant woman, it feels soft like the lips of the mouth, right? So it is called as Goodell's sign. And you can see this Goodell's sign or softening of the cervix as early as around six weeks of... gestation six weeks of pregnancy you can elicit this goodal sign as well right so aman hegar sign is not softening of the cervix hegar sign is softening of the isthmus this here portion is the isthmus so this portion here which i marked right now is the isthmus you It is the area just between the body of the uterus and the cervix here.
This is the area between the anatomical and the histological internal os. Okay, anatomical and the histological internal os, it enlarges during pregnancy and there's a lot of softening of the isthmus. Right. So what is the Hagar sign is that there is softening of the isthmus here and the pregnancy is here.
So if I'm doing a PV examination, if I'm doing a PV examination, one finger inside the vagina and the other hand on the, this thing, abdomen, you know, then I can approximate the two fingers. I can approximate the two fingers. So I, because it is so soft that my hand may able to, you know, dig in to the isthmus as well. So that is the good sign.
I usually have a picture of the good sign. But in today's chapter, I don't have that. In today's session, I don't have a picture of the Hagar sign there for you today. Now, Ayesha, you are saying, is this due to estrogen or not?
See, both hormones are going to contribute to the changes in the cervix, right? So your estrogen is going to be mainly responsible for the proliferation of the cervical glands and your progesterone is going to be responsible for the secretory activity of these glands. So both are going to contribute. Now moving on further, what are the changes in the vagina?
Now the changes in the vagina are also happening in anticipation of the pregnancy event only. So it is this vagina which is going to form the birth canal through which the baby is going to pass through during labor. So the vagina also undergoes a great amount of vascularity.
Increase in vascularity of the vagina takes place because see the blood flow through the uterine artery also increases, the blood flow into the pelvic organs increases, blood flow into the vaginal arteries increases, upper part of the vagina is also supplied from the branches of uterine arteries. So all in all, there is a greater vascularity of the vagina. You can find that the vaginal walls are also hypertrophied, right? the connective tissue of the vagina, the underlying connective tissue that also undergoes, you know, collagen degradation that also undergoes softening and water retention.
So the underlying connective tissue also softens, right? So what is the implication of this? This glater vascularity of the vagina leads to a bluish hue of the vagina, which is very subtle.
but can be appreciated during pregnancy. So what is this bluish hue of vagina which we appreciate during pregnancy? What is the sign called as?
This sign is called as the Chadwick sign or the Jackmere sign. And we are able to appreciate this sign by around eight weeks of pregnancy as well. So Chadwick sign or Jackmere sign is for the bluish hue of the vagina.
The reason is the greater vascularity of the vagina. Now, other than this, the vaginal pH. The vaginal pH is more acidic as compared to a non-pregnant state. Particularly acidic, the pH is around 3.5.
Now, what is responsible for this vaginal pH being more acidic? I mean, the same estrogen which in the non-pregnant state also leads to vaginal pH becoming acidic. It is this increasing amounts of estrogen which favor the vaginal pH. the growth of, you know, deposition of glycogen in the squamous cells of the vagina. So there is more of glycogen in the squamous cells of the vagina. And then this glycogen is used up by the lactobacilli, the healthy commensal bacilli of the vagina.
And that glycogen is metabolized to release lactic acid, right? So lactic acid is responsible for the excessive acidic pH of the vagina right now if they ask you if they ask you what is the most common vaginitis in pregnancy then what's your answer if they ask you what is the most common vaginitis in pregnancy then what's your answer so is it bacterial vaginosis is it trichomoniasis is it candidiasis so which is your most common vaginitis in pregnancy the fact is that the vaginal pH remains much more acidic there is increase of glycogen and that acidic pH flourishes the growth of fungi but furnishes the growth of Candida so for bacterial vaginosis Ebunisha your pH should be alkaline so most common vaginitis in pregnancy is vulvovaginal candidiasis frequently found in pregnant women as well. Now, let's move on further and talk about the breast changes in pregnancy.
Now, women, you see, often tend to complain or when they become pregnant, especially early on, from the very early on in pregnancy, you know, they start complaining of tenderness in their breast, they start complaining of a sort of tingling sensation, you know, some tightness of the breast, some heaviness of the breast. So, What are these changes and what is responsible for these clinical symptomatology? So there is a marked hypertrophy and proliferation of the ducts as well as alveoli of the breasts, all in anticipation for obviously a successful pregnancy and lactation. So there is hypertrophy proliferation of ducts.
For the ducts, what is required is estrogen. For the alveoli, estrogen plus progesterone, butyrate. is required. The vascularity, blood supply to the breast is also increased. So vascularity is increased.
There's hypertrophy of these sebaceous glands lying on the periphery of the areola. So what are these hypertrophied sebaceous glands called as? What are these hypertrophied sebaceous gland called as? I mean, they're not normally hypertrophied, okay, normal non-pregnant, but they become prominent and hypertrophied. in pregnancy what are they called as they are called as the montgomery tubercles right now the secretions from these you know hypertrophic sebaceous gland like the montgomery tubercles uh these secretions the function of these secretions is simple you know to keep the nipple area to keep the areola moist and healthy so that is one reason why the hypertrophic sebaceous gland occurs And after a time in the second trimester, you'll have a further pigmented area around the breast, which we call as the secondary areola, which will appear in the second trimester as well.
And from very early on in pregnancy, you see some secretions can be elicited from the breast. If you press the nipple, those are called as colostrum. So colostrum can be excreted and can be elicited from the breast as early as.
12 weeks of gestation, as early as 12 weeks of gestation and by around 16 weeks, you know, after 16 weeks, it starts becoming typically yellowish in color as well. So early on, it is clear less, but after 16 weeks, you can see a slight yellow discharge. If you press the nipple, that is called as colostrum. So these are the normal physiological changes in the breast. So if a woman is getting troubled by the fact that her breasts are feeling tense and tight and tender, and you know, if she's getting troubled by the fact that there's some discharge from her nipples, you know, she just needs to be counseled that these are physiological changes of pregnancy and she did not worry about it.
It is not that there is some cancer or there's some... you know, problem with her breasts per se. But having said that, pregnancy is a time when, you know, it is an opportunity for, you know, digital examination of the breast as well. So I want to emphasize on this here, that whenever you examine a pregnant woman, you know, make sure that you use this opportunity to palpate the breasts as well, so that a digital examination is done so that any abnormal lump or anything could be...
picked up. So preventive strategy should be put in place there as well. Now moving on further, what are the various cutaneous changes, skin changes that take place, physiological skin changes that take place during pregnancy.
So one thing that you can see from the figure here itself is the stria gravidarum. So these stria, these which we call as commonly called as the stretch marks of pregnancy. Don't we call them the stretch marks of pregnancy?
So they can be hyperpigmented. They might be slightly pinkish or they might be just scarish, white-like or, you know, over a period of time. So striagravudarum form because of the stretching of the skin, overlying skin when the uterus grows.
So that can be there. There can be a hyperpigmentation. which can be seen in pregnancy.
So it can be a hyperpigmented black line here extending from the pubic symphysis all the way up to the umbilical. So what is this line called as? This is what we call as linea nigra, right?
Now these hyperpigmentation changes which are taking place in pregnancy, they can also occur on the face. You see, they can occur on the malar prominences they can occur on the forehead and then they are called as the cloasma they're also called as the melasma of pregnancy but they are physiological changes and they are estrogen related changes mainly so there is some elevated you know melanocyte stimulating hormone which is seen during pregnancy estrogen also has some you know melanocyte stimulating hormone like effect. So yes, so that is responsible for the pigmentation during pregnancy.
And women tend to worry what will happen with these changes. Well, most of the times they're certainly going to lighten once the pregnancy is over, but they're not going to completely disappear. Now, other cutaneous changes which we can recognize in pregnancy are vascular spiders. So what are these vascular spiders, guys? What are these vascular spiders that I'm talking about?
So sometimes women complain of these, you know, rashes. I mean, women will feel that it's a red, red rash. But when you observe it closely, you'll see that, you know, she can have, you know, a centrally dilated red area and some radiating arterioles coming out of it.
So these are the dilated capillaries, you know. and there is a centrally dilated capillary and then there are branches which are branching out from the centrally dilated end. So these vascular spiders, you know, they are also occurring because of estrogen. And women might say that she's having those rash like things on her chest, they can occur on the breast, and they are more predominantly seen and appreciated in fair skinned women in fair skinned women.
so vascular spiders are a physiological phenomena and they are going to settle down once the pregnancy is over so you just need to counsel the woman you know that these changes are going to subside after delivery they're going to disappear and they're not going to leave any permanent disfigurement or you know they're not going to leave to leave any scarring or a permanent pigmentation there so she need not worry about these vascular spiders they are going to subside. So similar change is the palmar erythema, right? So redness of the palms, vascularity in the palms also increases.
Again, these are all both, you know, estrogen-related changes, estrogen-related changes which can be seen in pregnancy, but they are going to settle down once the pregnancy is over. Right. Apart from that, you know, pregnant women also say sometimes, you know, that she'll say that she's feeling feverish.
But when you measure her temperature, there will be no fever. Why is that? Why will she say that she's feeling as if, you know, they often describe the feeling heated up. They feel as if there is a lot of heat radiating from their scalp, from their palms.
And, you know, they all feel heated up. They feel feverish. So what is...
The reason for this? What is the reason for this? There is increased cutaneous blood flow.
There is increased cutaneous blood flow again mainly because of progesterone also contributed by estrogen. Both of these hormones contribute to cutaneous vasodilatation and it is basically in response for heat dissipation. You see progesterone is a thermogenic hormone. progesterone is a thermogenic hormone and also during pregnancy the metabolic rate is also increased in pregnancy so whenever the metabolic rate is going to be increased you see body heat production also increases so to get rid of that excessive body heat as well you know this increased cutaneous blood flow helps in heat dissipation from the body where there's an extra heat production because of an increased metabolic rate in pregnancy.
So this increased cutaneous blood flow is also something that is normal and physiological. So she might be feeling slightly feverish, but she's not. When you measure the temperature, it's not fever. Then the woman need not worry about it.
It's a physiological change in pregnancy. There is a lot of vasodilatation in all the circulations of the body which are taking place during pregnancy, right? Now, moving on further, let's talk about the metabolic changes in detail now, right?
Now, what am I going to do here in this session today is I'm going to give you an overview of the metabolic changes and tomorrow's session, I will be discussing the system-wise changes, all right? So let's get started here. So what happens during the metabolic changes in pregnancy? So to understand that, you see, there is a deposition of fat and protein stores in pregnancy that takes place.
You agree on that? There is a visible change in the woman, there is weight gain, right? And that for that weight gain to take place, obviously, there is a whole 3 kg fetus inside, there is a...
growing placenta inside, there's amniotic fluid inside the uterus. But apart from that, there is deposition of fat and protein stores, there is growth of uterus along with the fetus inside, there is growth of breasts as well, right? So all of these processes, you see, if the breast alveoli are growing and developing, if the muscle is undergoing hypertrophy, hyperplasia, deposition of fat, breakdown of fat, buildup of fat, transfer of protein everything is taking place all of these are metabolic processes aren't they right any transfer of material or nutrient from the placenta from the mother to the fetus's side needs energy right needs metabolism right so what will happen is you will see that to take care of all of these processes you see that there's a blood flow through the uterus increases Blood flow through the breasts increases, cutaneous blood flow is also increasing.
So to take care of the metabolic requirements of the fetus per se as well, you see, the placental perfusion needs to be established, right? So mother has to meet the requirements of the fetus also and herself also, right? So what happens here?
These are considered them two circulations in parallel. So it cannot happen that first the placenta will be perfused, then the mother will be perfused or first the mother will be perfused, then the placenta will be perfused. It is simultaneous.
These are two circulations in parallel. Now to achieve that, the entire circulating blood volume in the mother needs to increase. So one of the primary change that we see in pregnant women is that their blood volume starts increasing, right?
And like I described to you, that all of the processes that are involved in growing of the fetus, placental transport of nutrients, oxygen, growth of breast, deposition of fat, protein stores laid down, all these are metabolic processes. So the basal metabolic rate increases in pregnancy and it is important to remember it increases by about 25%. 25%.
Right. Now, one of the important hormones that is taking part in metabolism, in maintaining the basal metabolic rate is your thyroid hormone. So the thyroid hormone production needs to increase in pregnancy broadly. Right.
Now, if all your metabolic processes are going to take place, these are dependent on oxygen. You see transport of ions from one end to the other and transport of nutrients. Right.
These are all. Oxygen dependent processes, they require ATP, they require energy, they require oxygen. So your oxygen consumption in pregnancy also increases, isn't it? So your oxygen consumption in pregnancy increases by about 20%, right?
Now, if there is an increase in oxygen consumption, you see, when I need to consume more oxygen, I need my blood to have more oxygen. So I need my blood to increase its oxygen carrying capacity so that that oxygen can be distributed to wherever it is required. So the oxygen carrying capacity also increases in pregnancy of the maternal blood.
And to take care of this increased requirement of oxygen carrying capacity, oxygen is transported by hemoglobin by the RBCs. So the RBC mass also increases in pregnancy. So we see too broadly. So one thing is that to think about it in a wholesome manner, you see.
So all these metabolic processes require blood, they require blood perfusion, they require oxygen and therefore the blood volume increases in pregnancy. And so does the RBC mass increase in pregnancy. Now, the blood volume in pregnancy, it starts increasing by about 6 weeks and it reaches a maximum around 32 to 34 weeks of pregnancy.
Right. Now, what is composed in this blood? What is composed in this blood apart from...
your RBCs, WBCs, clotting factors, this and that. What else is composed in the blood? What is the blood made up of? It is made up of plasma, right?
So there are cell and there is plasma. So your blood volume increases by about a total of 40 to 50% in pregnancy, okay? And overall we are saying and your plasma volume increases about 40. to 50 percent 42 this is sorry this is blood volume increases about 40 to 45 percent your plasma volume increases much much more it increases about 40 to 50 percent and your RBC mass on the other hand increases only about 20 to 30 percent so we see that the plasma volume increases more in proportion to the RBC mass, right?
So, what does that lead to? That leads to, Ayesha was rightly pointing out, hemodilution. That leads to hemodilution. Now, this hemodilution is very protective for two reasons.
I mean, you will wonder why this hemodilution is required. I will tell you why it is required. Look at this.
This is a a diagrammatic representation of a blood volume showing hemodilution. I mean the RBCs are there, the RBC mass actually has increased but because of disproportionately increased, more increase in plasma volume, it's hemodilution. And then you have a hemo concentrated specimen.
You have a hemo concentrated specimen where your RBCs also increased but the plasma volume maybe did not increase that much. So hemo concentration. If I were to take out 500 ml of blood from both the specimens, who will end up losing up more RBCs?
Who will lose more RBCs? Who will lose more RBCs? The one woman who is hemo concentrated, she will lose more RBCs for per ml of blood because her blood volume is hemo concentrated.
So hemodilution is protective. Because at the end of the day, there can be no bloodless delivery. There can be no bloodless delivery. Some or the other amount of blood loss is going to happen during delivery, during delivery of the baby, during delivery of the placenta. After that point, you see, it is nature's way of protecting against losing more RBCs.
So, hemodilution is protective there. And secondly, The one other factor apart from uterine contractions you see which are preventing against blood loss after delivery because the uterus contracts back then obviously the body's coagulation mechanism also contributes right normal coagulation mechanism of the body also contributes. So what happens to the clotting factors in pregnancy guys?
What happens to the clotting factors in pregnancy guys? What happens to the clotting factors? What happens to the clotting factors?
All in all, it is a estrogen-related change due to estrogen. The clotting factors are increased. Yes, all factors increase. Very good, Alemu.
All factors increase. All clotting factors increase except factor 11 and factor 13. indeed fibrinogen fibrinogen increases by about 50 percent and that increase in fibrinogen and consequent increase in clotting factors it is responsible for increased erythrocyte sedimentation rate so if your blood is going to be hemo concentrated it is going to have a sluggish flow and all in all you for the past 10 minutes, I've been telling you that blood flow everywhere increases blood flow to the placenta increases to uterus increases to breast increase. So blood needs to keep flowing.
I don't want a sluggish blood flow during the nine months of pregnancy sluggish blood flow clotting factors increase or more incidence, more risk of thrombosis, right? So hemodilution is protective against that also. So it is protected.
against blood loss it is nature's way of protecting against blood loss it is nature's way of protecting against clotting it is nature's way of you know making keeping the blood flowing it keeps the blood flowing basically right so hemodilution is a very very important phenomena the clinical implication is that pregnancies where there is hemo concentration. Pregnancies where there is hemo concentration. Can you tell me one pregnancy where there is hemo concentration instead of hemodilution?
Can you tell me of one incidence of one example of a situation where there is hemo concentration instead of hemodilution? Very good, Elemu. Pre-eclampsia.
Pre-eclampsia. So you see, A woman who is normally hemodiluted without preeclampsia, right? She can tolerate 500 ml of blood loss, no problem.
But women with preeclampsia who are hemo-concentrated, they tolerate blood loss poorly. They tolerate blood loss poorly. If you compare a pregnant woman without preeclampsia losing the same amount of blood and a woman with preeclampsia losing the same amount of blood, preeclampsia losing the same amount of blood, the woman with preeclampsia is going to become more symptomatic, more affected, right? So they tolerate blood loss poorly.
That's a very, very important point for you guys to remember. Again, a very, very important clinical implication, right? Now, moving on further, let's dig in further deeper into this water retent, into this blood volume. I want to dig in further deeper.
into this increase in blood volume. So I told you that RBC mass is increasing. I'm telling you that the plasma volume is also increasing.
So blood has a lot of plasma and the plasma volume needs to increase. Now what is the plasma composed of? What is the plasma composed of? Plasma is cell minus whatever remains of the blood volume is the plasma. It contains of coagulation factors serum right that is all water Isn't it?
That is mainly water. So there is a lot of water retention in pregnancy. There is a lot of water retention in pregnancy.
How much? The next question is how much water is retained during pregnancy? How much do you think is this water retention in pregnancy?
Total, yes. total of about 6.5 liters around 6.5 liters of water retention in pregnancy out of this 3.6.5 liters you see some of it is in the fetus some of it is in the placenta some of it is in the amniotic fluid so this much bit is about the fetus placenta amniotic fluid together is about 3.5 liters where's the rest The rest 3.5 liters is in the blood volume, 3.5 liters distributed in the blood volume, distributed in the tissues of the breast, distributed in the tissues of the uterus and it is all in the extracellular compartment. It is not inside the cells, it is in the extracellular compartment, in the extracellular spaces, right. Now moving on further, The next question that arises is how is it that in a pregnancy a woman is able to retain so much water? So Ayesha is saying water due to estrogen.
I gave it to her very correctly said that one of the reasons is estrogen. So there are two reasons basically. When you need to increase your water retention by your body, you will end up either drinking more water, isn't it? Or you'll end up by your kidneys.
absorbing more water, retaining more water. So these are the two mechanisms by which anybody can increase their water retention, right? So what happens in pregnancy is that the osmotic threshold for thirst decreases.
What does that mean? That means, you see, I'm sitting right now, I'm talking to you guys, I'm taking this session, you know, and my throat is feeling a little bit dry and then obviously maybe I've not had enough water to drink for the whole day and then, you know, my plasma will become a little bit more concentrated, osmolality of my plasma will increase and that will send a trigger to my brain and then I'll feel thirsty and then I'll drink water, right? Now, what happens in pregnancy is that the threshold of osmolality at which a person feels thirsty, starts to feel thirsty is decreased. So pregnant women, they drink a lot of water because of that reason, right? So osmotic threshold for thirst decreases, the plasma osmolality also decreases not much, but just about by 10 milliosmol per liter, right?
So that's one reason you end up drinking, pregnant women end up drinking more and more water. The other thing is water retention. Now, like I told you that salt and water retention has to be happening together, right?
So only plain and plain water will not be retained. Salt, that is your sodium and potassium will also be retained simultaneously. And this is a direct effect of estrogen on the kidneys, right?
Estrogen is going to stimulate The one system which is responsible for water retention outside of pregnancy also, how do the kidneys end up retaining water and salt? By stimulation of renin-angiotensin-aldosterone system. So that is a direct effect of estrogen on the kidneys, salt and water retention.
But yes, water is retained much much more as compared to salt retention overall. Now, when you say that sodium and potassium ion are retained from the kidneys, does that mean if you were to take a blood sample from a pregnant woman and measure the sodium and potassium concentrations, let's say that I ask you to take a blood sample of a pregnant woman and I ask you to measure the sodium and potassium concentration. What will you find? Will she have hypernatremia? Will she have hypokalemia?
Will she have that? No, she will not have that because simultaneously water is also being retained. So the concentrations in the serum, they are maintained in the normal range or maybe even slightly lower normal range or maybe slightly lower, but still in the low normal range. Okay, so she will not have any abnormality in the serum and potassium concentrations. Okay, so salt and water retention by the kidneys is also contributing to the water retention in pregnancy.
Now moving on further, I'll have to just maybe slightly clear this out. Okay, let me just slightly clear this out. And let me just elaborate and elicit one more point to you here.
So now that we see that the blood volume is all increased, there's a lot of blood volume, there's a lot of blood volume, 45 to 50 percent increase, right? So from being about, let's say, a normal blood volume of 5 liters, a pregnant woman at term will have a blood volume of 8 liters. Now where is all that extra 3 liter blood where is all that flowing obviously some part of you will say that it is in the placenta some of it is in the circulation but yet it has to be accommodated somewhere isn't it now it gets accommodated in the peripheral vascular system right remember we call them as the capacitance vessels why do we call them as the capacitance vessels because they can increase their they can dilate and they are dilating in response to the pregnancy hormones your progesterone your estrogen and locally related locally released nitric oxide so yes there is a decrease in peripheral vascular resistance that is because of vasodilatation and how is it reflected If you were to measure the BP of a pregnant woman, what are you going to find? What's her BP going to be?
If her BP is 100 by 60, you say she has hypotension? No, her BP actually falls. So blood pressure naturally falls during pregnancy. And which blood pressure falls more? Does the diastolic blood pressure fall more or the systolic blood pressure falls more?
It is the... diastolic blood pressure which falls more in pregnancy right now moving on further let's talk about the clinical implication of this important all the overview we have seen let's talk about the clinical implication so Ayesha said rightly pregnancy edema so all that peripheral pooling of the blood right all that peripheral pooling of the blood right, peripheral pooling of the blood, all that compression of veins by the gravid uterus, isn't it? And some of hypoproteinemia, right?
So in pregnancy, usually the albumin amount, the total albumin amount in pregnancy actually increases. But because of hemodilution, because of hemodilution, there is hypoproteinemia. So all of these three factors, they operate in causing a pitting edema over the ankles and legs, which will subside with the period of rest. So usually a woman will have it more often in her late pregnancy, more often at the end of the day when she's been walking around or doing things of the daily routine.
And when she gets up from bed in the morning, it will not be there. So this is a dependent edema, it subsides with rest and this is a physiological edema in pregnancy. But an edema which does not even subside with rest, an edema which is non-pitting, an edema which is excessive, I mean if the edema extends all the way up to her knees or if it's a generalized edema, then you start thinking of problems.
One problem that you start thinking of is possibility of preeclampsia. right so physiological edema in pregnancy is another important clinical implication the other important clinical implication is that of you know you've seen sometimes women complaining of this dizziness and syncope in pregnancy i mean she'll say that you know i was doing just nothing i was simply sitting doing my work on my laptop like this and then suddenly you know i just felt sudden blackout and dizziness and she's all worried So this dizziness and syncope in pregnancy is something that is normal and physiological. And that happens because of low BP in pregnancy. And like I said, that it is going to be especially so in about 24 to 26 weeks of pregnancy. Can anybody tell me why?
Why will it be that a woman more so in her second trimester, like 24 to 36, 26 weeks, is going to complain of... Dizziness and syncope in pregnancy. I told you it's because of low BP and it's particularly prominent here because so this is a BP in the first trimester. This is her BP in the first trimester or sorry this is a pre-pregnancy BP let's say. It starts when she gets pregnant, it starts falling, falling, falling and it reaches its lowest.
at around 24 to 26 weeks. Thereafter, the BP picks up again. Why does the BP pick up again?
Because of rising blood volume. So initially, the low BP was because of decreased peripheral vascular resistance. But as and when she reaches 30-32 weeks, you see the blood volume also has been rising, right? And that is responsible for further increase of BP.
in the second half of pregnancy and thereafter the BP is going to stabilize, but still at a lower level than her pre-pregnancy level. So knowing these trends in low BP is also important because A it helps you to counsel the woman regarding the kind of symptoms that she's getting. right?
So if she's having dizziness and syncope, all you need to tell her is there's nothing to worry. She just needs to lie down for sometimes, preferably in a left lateral position. She'll feel better. This syncope dizziness will pass over in a couple of minutes.
All right. The other important implication is that hypertensive disorders of pregnancy, pregnancy induced hypertension, like gestational hypertension or preeclampsia, they are presenting after 20 weeks of gestation. They are normally presenting after 20 weeks of gestation because it is then when your BP rises, right?
Whereas a woman who is presenting with high BP in her first trimester, high BP in the first 20 weeks of pregnancy, here somewhere high BP in the first 20 weeks of pregnancy, then we start thinking maybe this is chronic hypertension. We start thinking maybe she has hypertension from before only because in the first 24 to 26 weeks BP should actually fall but if there is high BP in the first 20 weeks we start thinking maybe this BP is from pre-pregnancy only maybe this is chronic hypertension right so this is the clinical implication of understanding low BP in pregnancy. And let's now come to another clinical implication. Another clinical implication of hemodilution, which has been left out, another clinical implication of hemodilution is physiological anemia in pregnancy. Physiological anemia in pregnancy because you see that is despite the increasing RBC mass, despite that, because there's a lot of hemo.
So a woman who in her pre-pregnancy or who started her pregnancy with an Hb of let's say about 12 g per deciliter, by the time she reaches around 32 weeks, this hemodilution is enough to make her Hb about 10 g per deciliter. These are all approximately. So approximately there can be a fall in hemoglobin concentration of about 2 gram per deciliter because of hemodilution, right?
Now this hemodilution and this physiological anemia is maximum at around 32 weeks of gestation. That is the same time when your blood volume changes are also maximum, right? Now the implication is that it is very very important to check the hemoglobin of a pregnant woman in the first visit itself so that we can put preventive measures in place and thereafter repeat in each trimester thereafter repeat in each trimester because every woman who gets pregnant will have some degree of physiological anemia right now to increase the RBC mass in pregnancy that is to increase the hemoglobin mass ultimately hemoglobin mass is also increased one needs more of iron isn't it these RBCs needs to be hemoglobinized so the iron requirement increases in pregnancy the question that they ask you in exams is how much how much is this increase in iron requirement in pregnancy So the total iron requirement in pregnancy increases is about 1000 mg. Out of these 1000 mg, the fetus and placenta need about 300 mg, right? Fetus also needs to make its own blood volume.
For that, it needs iron from the mother. RBC mass increase in total needs about 500 mg of iron. And of course during the nine months of pregnancy there's going to be some obligate loss like iron is lost through the gastrointestinal tract, iron loss through way of sweating, some iron loss, little bit of iron lost in the urine.
So there are obligate daily basis losses of iron which are taking place throughout the nine months of pregnancy as well. So total all in all the total requirement of iron is 1000 milligram. Important to note that the distribution of this iron requirement in the first half of pregnancy is about 3 to 4 milligrams per day.
This is the iron that should reach the bloodstream. This is the iron which should ultimately get absorbed. Okay. And in the second half of pregnancy, it's about 6 to 7 milligram per day.
Now, knowing this is important because you'll realize if I ask you, if I ask you, When do you start a woman with the oral iron tablets in pregnancy? When do you do that? You start oral iron tablets in pregnancy, not in the first trimester, but from the second trimester onwards, but from the second trimester onwards for two reasons. One is that the most of the iron requirement is distributed in the second half of pregnancy.
Secondly, if you want to prescribe oral iron tablet in the first trimester of pregnancy, in the first trimester, woman is anyways having a lot of nausea and vomiting, you see. So she will not be able to tolerate the oral iron tablets. For this reason, when you start oral iron tablets in pregnancy, you start them in the second trimester. Okay, now new concept I'm talking about oral iron.
Iron, when you say before conception, that is folic acid for the prevention of neural tube defects. When you say preconception, then that is oral folic acid, not oral iron tablets. Okay.
Now, how is it reflected? What is the clinical implication of knowing that there is physiological anemia of pregnancy? That's because the diagnosis of anemia in pregnancy changes, doesn't it? I mean, outside of pregnancy, your hemoglobin values are different as far as normal values are concerned.
But in pregnancy, to diagnose anemia, anytime your Hb is less than 11, so your lower limit is lessened. So Hb less than 11 gram percent is the diagnosis of anemia in pregnancy. or a hematocrit or a packed cell volume less than 33%. That is your diagnosis of anemia in pregnancy, right?
So you see that despite an increasing RBC mass, despite that due to hemodilution, your absolute hemoglobin concentration that you measure in the blood decreases, right? Your hematocrit decreases. right your platelet count decreases your platelet count also decreases because of hemodilution so all of these changes are reflecting hemodilution so your platelet count decreases to how much to how much from a normal 1.5 lakh platelet count can decrease to 1 lakh platelet count can decrease to 80,000 also but You have to understand that when your platelet count is less than 1 lakh, then you start thinking in terms of preeclampsia, possibility of preeclampsia. So platelet count decreases, yes, that is true, but it usually remains around 1 lakh.
It usually remains equal to a more than 1 lakh, above that. If it falls below that, you start thinking about the possibility of preeclampsia. Yes, new concept, thrombocytopenia is what is. platelet count decreases. Serum iron concentration also decreases, right? To meet the iron requirements of pregnancy, the maternal stores of iron are mobilized.
So your serum ferritin also decreases because ferritin reflects your iron stores. Your total iron binding capacity because your mother is increasing. iron absorption from her diet right the iron absorption that you're giving her in the form of iron tablets she's increasing that so she needs to bind all that iron isn't it so the total iron binding capacity increases so you see the top four five things i told you they all decrease but your total iron binding capacity increases in pregnancy and what happens to the mean corpus mean corpuscular hemoglobin What happens to your mean corpuscular hemoglobin concentration? That remains the same. That remains the same.
That remains the same because each of the individual RBC that is formed is properly hemoglobinized. Now, the next thing I want to ask is what happens to the MCV? What happens to the mean corpuscular volume?
So, let's see this here. There's this RBC, RBC number, this, this, this, this, this, this, this. So you see what I've done?
I've drawn some larger RBCs. I've drawn some larger RBCs. Each of these RBCs are properly hemoglobinized. So mean corpuscular hemoglobin concentration, concentration in a single hemoglobin mean, corpuscular hemoglobin concentration, that means the same, right? But when you see in pregnancy, RBC production is increasing, RBC production is increasing, right?
So you have some younger RBCs in circulation which are larger, right? So when you measure the mean corpuscular volume, it is slightly larger, it is slightly increased in pregnancy. So the mean corpuscular volume is slightly increased in pregnancy. That's because of increased RBC production, throwing of more younger RBCs into circulation.
All right. And new concept, vitamin C given with iron supplement. Yes.
And that is given to increase the rate of iron absorption, to increase the rate of iron absorption. Now, moving on further, let's talk about thyroid metabolism in pregnancy, right? Now, what happens to thyroid metabolism in pregnancy? Like I told you, there's an increased demand by the mother herself also to meet her basal metabolic rate requirements. Other than that, there is an increased demand by the fetus as well, right?
Because the fetus you see, particularly in the first 12 weeks, particularly in the first 12 weeks, is totally dependent on metabolism. maternal thyroid hormones on maternal thyroid hormones. So the fetus also needs thyroid hormones and they are helpful in the growth of the fetus's brain.
But for the first 12 weeks, neither is the fetal thyroid functional. So fetus is not producing its own thyroid hormones. Neither is the fetal pituitary functional, right? So it is totally dependent on maternal thyroid hormones for its own needs.
Indeed, TRH, thyrotropin releasing hormone, T3 and T4 hormones, they can freely cross the placenta. They can freely cross the placenta, but not TSH. But not TSH, right? So, fetus is totally dependent on maternal transfer of thyroid hormones to itself, to the fetus in the first 12 weeks of pregnancy. So, your...
Increased metabolic requirements by mother herself plus fetus puts a strain on the maternal thyroid. So thyroid hormone requirement increases, iodine requirement increases by the mother. If a mother needs to produce more thyroid hormones, iodine will be required for that.
So iodine requirement increases to about 250 milligrams per day, right? And thyroid gland hyperplasia. and there is increased vascularity of the thyroid gland and all along the production of thyroid hormones all in all the production of thyroid hormones in pregnancy is increased Right?
Now, what is the clinical implication? To understand that clinical implication, let us just go through this chart once, right? So you can see here that early on in pregnancy, yesterday's session, we talked about HCG.
And I showed you that HCG increases in the first reaches a maximum peak at about 8 to 10 weeks, right? So you can see here that HCG also has thyrotropic activity. So it is this HCG hormone that is coming from the placenta that is stimulating the maternal thyroid hormone production from the thyroid gland.
So initially in the first trimester what we see that the free T4 levels they rise. Can you see the free T4 levels they are rising in the first trimester. So free T4 levels they are increasing in the first trimester.
As a result of these increased free T4 levels, there is a feedback inhibition to the maternal pituitary, right? So what will happen? The TSH, thyrotropin is TSH. TSH production by the maternal pituitary decreases. So what we see that in the first trimester, Your TSH levels are actually falling.
TSH levels fall. Serum TSH levels fall. But as pregnancy advances, what happens?
As pregnancy advances, what happens? This. The total thyroid binding globulin, TBG, thyroid binding globulin production also increases from the maternal liver. Now this is again happening because of estrogen, right? So thyroid binding globulin is going to bind to the thyroid hormone, right?
So what we will have? We will have, when it is going to bind to the thyroid hormones, we will have the total thyroid hormone production is increased. We can see the total thyroid hormone production levels are increasing consistently.
But your free T4 hormone levels, free T4 hormone levels, they normalize because thyroid binding globulin hormone production was also increased and this binds the thyroid hormones in circulation. So your free T4 levels, they normalize, they normalize, isn't it? So in a nutshell, what can we say?
In a nutshell, what can we say? If we say at term, at term what happens? Your total T3 and total T4 values remain increased. Your free T3 and free T4 values remain the same and your TSH levels overall, they are slightly in the low normal. range.
So it initially fell down, TSH initially fell down in the first trimester but it is again comes back to rises in the second trimester and then normalizes at a stabilizes at a slightly lower normal range as compared to the non-pregnant state. So this is very very important to understand. You can remember this in a nutshell as to what happens at term. But it is particularly important to remember what happens in the first trimester because the clinical implication is in the diagnosis of hypothyroidism in pregnancy. Like if I were to give you a scenario like this, that there's a 28-year-old obese woman who comes for an antenatal visit at eight weeks of pregnancy and she has a herself has a strong family history of hypothyroidism.
So you did a thyroid function test for her, you realize that the serum TSH is 3 miu per liter, 3, 4 in the normal range. So if you are not aware of the pregnancy related changes, you will say this is normal, right? But I will say this is not normal.
I will say that this is subclinical hypothyroidism. Because in the first trimester, you see here, the TSH level actually falls. So to call hypothyroidism, I will have to adjust the upper limit of TSH hormone at which I will call it as hypothyroid.
So, the upper limit changes, right? So, being in this range, 3 MIU per liter may be normal in non-pregnant, but it is not normal in pregnant women, right? So, it is subclinical hypothyroidism.
Why? Because the free T4 is normal and the TSH is raised. I will call this as raised.
It's not overt hypothyroidism, but it is an overt hypothyroidism. The free T4 will be also be low and your TSH will be raised, right? So that's why this is subclinical hypothyroidism. So the diagnosis of hypothyroidism changes. That's the clinical implication of understanding this changes.
So rightly said, Peter. And Kostub now answering to you. The upper reference limit is most important to remember. The upper reference limit for serum TSH considered during pregnancy is in the first trimester 2.5 and in the second and third trimester 3 MIU per liter.
So if it's more than 2.5 MIU per liter in first trimester consider it raised TSH. If it's more than 3 MIU per liter in second and third trimester consider it raised TSH. Okay? So that's the difference there.
Now, coming back to the last leg. What about the calcium metabolism in pregnancy? Right.
So what happens to the calcium metabolism in pregnancy? You see, the fetus itself needs a lot of calcium. Fetus has to make its own bone.
P-fetus has to make its own skeleton tissues and everything. So fetal needs an extra in total of about... 30 grams of calcium from the mother.
Now, so to meet this excess requirement of calcium, you know, mother needs to increase calcium absorption from her gut. That is very important because if the mother's dietary intake of calcium is deficient, you see, then she will start, the baby will take the calcium, you see, and then the mother will start leaching out it from her. bones.
So that should not happen in pregnancy, isn't it? You agree? So it's not like Mudan should give it from her bones.
So mother needs to increase the calcium absorption from the gut. And for that, there has to be increase in 1,25, the activated form of vitamin D levels. Again, these are estrogen related changes, right?
So more activated vitamin D levels are seen in pregnancy. A woman ends up absorbing more calcium from the gut, but yes, she has to have a calcium rich diet. If she's not taking a calcium rich diet, calcium supplementation pregnancy needs to be done to meet this increasing requirement of calcium, right?
And the total serum calcium actually increases, right? The total serum calcium actually increases in pregnancy but what happens to the ionized calcium levels? What happens to the ionized calcium levels?
They remain the same because it is the total calcium. You will have the total calcium levels in the serum. Then you will have the bound form of calcium that is bound to albumin, right?
So the one that is bound increases, right? So total increases, bound increases, it's because of the bound fragment that is increasing, right? And your ionized forms, ionized calcium, those levels remain the same. Those levels remain the same, right?
So this is another important implication that you have to remember. A new concept you are telling me, 1500 milligram per day, it's about 1000 milligrams per day. It's about 1000 milligram per day, right?
An extra of 500 milligram, an extra of 500 milligram, it's about 1000 milligram per day, calcium requirement in pregnancy. Okay. And this with this, I will finish off the session for today.
So today we've discussed the metabolic changes, the important metabolic changes. And tomorrow we are going to discuss Tomorrow, we are going to discuss same time on YouTube, 4 p.m., the systemic changes and their clinical implications. Okay, so that will be the second session of physiological changes in pregnancy.
And tonight, guys, at 8 p.m. On the special live class, I'm taking up prenatal screening. I'm taking up prenatal screening.
This is a free live class. So you guys can join me there as well. And Aman, if you're still watching, if you want, I don't know if you're still watching. Otherwise, I would have cleared your doubt. Just give me a feedback regarding because you asked a question at the end of the session.
So now, any further doubts and queries regarding today's session, please feel free to put them on the chat box. I'm looking if there are no further doubts and queries, I'll end the session for today. Lemu, how can you get the presentation? Unfortunately, when on YouTube, these are ppt these are presentations which are not uploaded i mean you can always download the video but you cannot get the pdf format but if you attend the special classes i mean those what there whatever is the presentation whatever i write extra everything you can get downloaded in a pdf format but that's possible for the special classes unfortunately it's not possible for the youtube sessions which i conduct live i mean you can download the videos at a later point in time but not you can't get the PPTs or the PDF formats of them. Okay.
Yes, Alamu, even after the end of this live session, when it ends, you can download it. You can download it. Okay.
So these are free videos. You can download them. All right. So if there are no further questions, I would like to. All right.
So Alemu and Emanuel Brooks. Now see these special classes that I have undertaken, the special classes, there is a series of special classes. that I've already undertaken over the past couple of months and I always I'm in the process as well I keep taking new and new session now these special classes are free so they are free you can join me there at the end of the session you can download the ppts and presentations also so they are free and for these subscription packages I mean there's certain special class certain plus courses so there are certain plus courses as well For that, you'll have to subscribe to the platform.
Okay, you'll have to buy a subscription package. And the rates of the subscription package, I have told them about. So of course, I don't remember them on my fingertips.
But then I've told about them in the beginning of the session, there's the rate list that comes. So if you can take you can take those subscription packages, depending on whatever you need, you need for a month, you need for three months, six months, whatever. But if you can use the code. that is my code you will get a 10% discount additional on your subscription packet so that has been described in the beginning of the session so just after the end of the session or in my previous session you can just see the beginning two to three minutes of the video they're there so that will help you in deciding so if there are no further questions I would end the session for today thank you so much and Have a great day.
Take care. And I would emphasize on Telemu again. Telemu, these labor sessions, they were free.
So you can join and see them on the Unacademy platform. And there you will be able to download them as well. Okay. So have a great day, guys.
Take care. Thank you.