Welcome friends, today we are going to see the topic of physiological changes in pregnancy. We all know that baby is growing in the mother's body and developing its own systems like baby's own cardiovascular system, blood, calcium required for bone formation, skeletal system. So when baby needs all these things, mother's body is trying to provide all these things to the baby. As well as when baby is growing, there are many changes which are taking place in mother's body over the period of 9 months to adopt this particular fetus, this particular parasite and to accommodate the life of these two both, the mother herself and the baby.
So these changes they occur almost in all the systems of mother's body. Let's first begin with some signs of pregnancy because this is important from MCQ point of view. Early detection of pregnancy from some signs.
Chadwick sign, it is seen at 8 weeks. What is it? It is the bluish discoloration of the vaginal mucosa or vestibule. Because of lots of blood supply, congestion. The vestibule and majoral mucosa appears bluish and that is jatvimers or jatvik sign, usually seen around 8 weeks.
Ossian does sign again at 8 weeks, it gives feeling of pulsation to the lateral fornices. Again, because of gravid uterus, lots of blood supply. The cervix changes, the consistency changes because of pregnancy.
The moment you start doing PV examination of pregnant lady, you feel that The normal cervix which feels like cartilage, maybe this cartilage of bone or the nasal cartilage, this cervix now starts feeling like lips. It becomes very soft. So to touch, the cervix appears like lips and that sign is called as Goodell's sign. Again, 6-8 weeks is the duration when you start feeling these signs.
Piscus is sign in case if the pregnancy gets laterally implanted and you examine such patient by per vaginal exam. you feel half of the uterus is more firm than the other half because of lateral implantation and this is piscisage sign. Hagar's sign. In Hagar's sign because of implantation in the upper part the upper body of the uterus enlarges.
Lower body comparatively it doesn't enlarge much. So when you do PV examination your fingers can approximate and literally you can feel through the uterine body the upper portion and the lower portion can be different. So this is called as Hegar sign, 6 to 10 weeks is the duration.
Parmah sign, from 4 to 8 weeks that you feel regular and rhythmic uterine contractions because of the myometrial contraction, that's Parmah sign. So not all but few signs you can surely use for clinical diagnosis of pregnancy. So if someone comes with amenorrhea and you put a speculum and you see that the cervix appears bluish, the vagina appears bluish, it tells you that she is most likely to be pregnant. Then when you examine the soft feel of the cervix that is the good sign surely gives you a clue that she is pregnant.
Other signs are not really useful in practice but they are useful from your exam point of view. So let's see now what are these changes which are taking place in maternal body. To begin with the most important organ which bears the fruit that is the uterus. Uterus changes all over. Body of the uterus, it is the musculature, three types, outer is longitudinal, inner is circular and intermediate fibers, they are intermingled, figure of eight, living ligages.
There is hypertrophy and hyperplasia of uterine body and it increases in size. These two changes, they happen under the influence of the major hormones that is estrogen and progesterone. Vascularity also changes.
As it is growing, it needs more blood supply. In non-pregnant uterus, we all know that uterus is getting blood supply from uterine vessels as well as from the ovarian vessels. If the woman is not pregnant, the uterine blood supply coming through uterine vessels is more than through the ovarian vessels. But in pregnancy, first it equals and then gradually ovarian becomes more. But uterine is also increased quantity.
The shape, it's piriform in shape. As the pregnancy advances around 12 weeks it becomes globular and then around 28 weeks it again becomes oval or piriform. When you examine this uterus you will feel that While examining, for some time the uterus appears hard and some it appears relaxed or soft. These are because of the contractions in the myometrium.
And these are called as Braxton-Hicks contraction. This is very normal physiological contractions of pregnancy. They are not painful.
So these are painless contractions. They are just felt irregular or at certain interval. but never associated with cervical dilatation and effacement. So these are physiological contractions called as Braxton Hicks. The usefulness of these contractions, they are absent when the pregnancy is outside the uterus.
That means if the pregnancy is abdominal, then Braxton Hicks contractions are absent. Again, a very important MCQ, the use of Braxton Hicks contractions. From body then coming to isthemas.
Isthemas is a very tiny part of uterus but it has a major role in pregnancy. What is isthamas? MCQ can be there. From the anatomical internal os to the histological internal os, the distance 0.5 centimeter is isthamas and below which is the external os.
So in first trimester, this isthamas hypertrophies and increases almost three thrice the size of its and in second trimester, it starts unfolding. it starts unfolding that means the portion starts getting incorporated in the uterine segment and lower uterine segment purely forms from this isthmus and significance of lower uterine segment that it is covered with a loose fold of peritoneum and lower segment caesarean section is done through the lower segment of the uterus. What happens to the cervix?
There is trauma, there is hypertrophy and hyperplasia, vascularity increases, and that leads to softening of the cervix. We have already seen its good health sign. And the secretions, there are copious and tenacious secretions under the influence of progesterone. And these mucus plug, they are important to avoid or to stop ascending infections. Now the other organ which is important is breast because immediately after delivery, lactation plays a very important role in the development of the fetus.
So preparation of this lactation. which is actually required after the delivery starts during pregnancy. Breast, there is hypertrophy and proliferation of glands.
The nipples, they become large, deeply pigmented and erectile. This formation of secondary areola. Whatever the areola normally present, there is again formation of secondary areola around it with the pigmentation.
Montgomery's tubercles, they are there and there is presence of secretion. So, in a patient who is never pregnant before, If you get secretions, that is again suggestive of pregnancy. So breast secretions is again a sign of pregnancy in a lady who has never been pregnant before.
Now coming to different important systems of maternal body. The first important system is cardiovascular heart. What happens to the heart in pregnancy? As the pregnancy advances, the heart gets pushed upwards, outwards and there is rotation towards left.
So the apical bit from its normal position the apex would get shifted to the fourth intercostal space 2.5 centimeter away from the mid glabicular line So the location gets shifted. Heart rate it increases by 10 to 15 beats per minute than her basal heart rate in non-pregnancy. There is split first heart sound there can be systolic murmur or mammary murmur because of increased blood supply The cardiac silhoutte increases in size.
If you compare non-pregnant and the pregnant heart, pregnant heart would be little bigger. And on ECG, there would be physiological left axis deviation. These were the changes in heart.
But now what happens to the function of the heart? Cardiac output increases. Because now the heart has to pump not just for her own body, but as well as for the fetal circulation, placenta, fetal placental circulation.
So the cardiac output increases. It starts, this is very important what we are going to discuss right now because in cardiac disease patient where the heart is ailing or not very perfect, not a very healthy heart, this overload which is going to be caused because of pregnancy, that heart may not cope up. So understand how are the changes. The cardiac output starts increasing by around 5th week.
35% increase in the cardiac output is by 12th week. And the peak rise, that means almost 1.5 times the normal, that is 40-50% rise is around 30-34 weeks of pregnancy. Rest of the pregnancy, that rise remain.
60-100% rises during labor, stress of labor. She is having pain, so any pain, if I pinch you severely, there would be response. Pain causes tachycardia, cardiac output would increase.
She is in tremendous pain. that increases cardiac output but the highest rise is right after delivery. When the baby comes out, the aortoceval compression effect of the gravid uterus disappears and uterus retracts and whatever blood till now was flowing through placenta and the uterus is now back to her own circulation. Some blood she loses in third stage.
But rest of the blood is back into her circulation, almost rest everything. This is auto-transfusion and this suddenly increases the load on the heart. So why these things are important?
Because when we are monitoring a patient of heart disease, we have to know that when she is likely to go in heart failure. That cardiac failure is the most common complication. So when this heart is going to fail? When the load would increase? So when are the maximum chances?
The chances the changes would start initially then peak at around 32-34 weeks. So we should be careful that may be the time when she lands up in failure. During labor, yes during labor because of contractions, because of pain, because of tachycardia, she may land up in failure and the highest chances immediately after delivery. When there is shift of blood from the uteroplacental circulation to her own circulation, that ailing heart may not be able to take this load. and that's why it may fail.
So we have to be very cautious during these phases and that is why it is important to understand the normal physiological changes. The cardiac output is lowest when she is sitting on in supine position because gravid uterus is pressing on the vena cava, venous return is decreased and thus it decreases the cardiac output. But as soon as the patient turns to left lateral position this pressure effect is gone and that increases venous return. and thus it increases the cardiac output. Now let's see what are the hematological or cardiovascular other changes.
Vascular, peripheral vasculature, there is decreased tone and vasorelaxation because of the hormonal effects. Progesterone, estrogen and also these hormones they cause peripheral vasodilatation, relaxation. So that decreases the systemic vascular resistance and it is decreased by 20 percent and because of which there is fall in the blood pressure. Specially diastolic blood pressure falls and thus the mean arterial pressure falls during pregnancy by 5 to 10 millimeters of edging.
Positional effect, again gravid uterus, it presses, venous return decreases. Because of that there may be renin angiotensin activation. So that effect would be seen in rollover test. Placenta, it is a low resistance shunt.
placental blood flow very less resistant we want the blood to enter the legs transfer of good things from mother to baby bad things from baby to mother should take place so low resistance shunting supine hypotension syndrome or postural hypotension syndrome is very common in pregnancy because if she's lying down supine vena cava is getting compressed by the gravid uterus usually third trimester then Actually, physiologically the collateral circulation should help her and the blood flow towards brain should be normal. But sometimes these collaterals, they fail. And at that particular time, because of decreased venous return, she may feel syncope or giddiness or tachycardia can be there. So this is very common in pregnancy. This is called as supine hypertension syndrome.
Again, a very likely question to be asked. What is the treatment? Are we supposed to give her some drugs? No, simple treatment from supine position just change her to left lateral. The pressure effect is lost and venous return will improve and thus the syncope would be avoided.
What are the pregnancy adaptations? So let's see the changes. Cardiac output increased almost by 43% in pregnancy. Mean arterial pressure, it falls by 10%. Systemic venous resistance falls by 21%.
Peripheral vascular resistance falls by 34% and heart rate is increased almost by 17%. Hematological system. We know that now the mother has to give blood to the fetus. It has to provide hemoglobin to the growing fetus.
So she has to increase her blood volume which is normally 5 liters of our own. Now some volume she has to send to the placenta, some to the fetus. So the blood volume has to increase. Hemoglobin has to increase.
Plasma volume has to increase. So These all things increase during pregnancy. Blood volume by 30 to 40 percent, plasma volume more than RBC.
Plasma volume increases by almost 40 to 50 percent and rise in RBCs is only 20 to 30 percent. So the cumulative effect of all this is there is hemodilution. This is quite physiological that the blood will flow very nicely because it is little diluted.
Again Whatever losses she would have in the third stage, she will not lose much of the RBCs. So body has caused relative anemia or physiological anemia and there is hemodilution. What happens to the clotting and bleeding factors? There is hypercoagulable state.
All clotting factors are increased except 11 and 13. So that leads to this is because of estrogen and the vascular stasis. may increase the risk of thromboembolic disease. So pregnancy, she always have more risk of having thromboembolic diseases in pregnancy.
The fibrinogen factor 1 also increases, that is also by 50%. So to remember the changes in hematological, there would be fall in hemoglobin. Why? Even though there is increase in RBC, it is comparatively less.
Plasma volume is more increased, so hemoglobin will fall. Paxil volume will fall, blood viscosity will fall, platelets and other factors 11 and 13 they decrease but there is little increase in WBC count. Ion metabolism again related with our anemia chapter. We know in India anemia is very common so we have to understand what are the changes taking place in ion metabolism physiologically then we will understand the pathology. So absorption of ferrous salt They usually take place in the duodenum and jejunum.
Then released in circulation as transferrin and transported to the fetus across placenta. If the lady gets enough iron from her diet, that is sent to the baby first. But if she doesn't get much iron from her diet by any means, then naturally from her own iron stores, iron is sent to the baby so that baby can form its own.
vascular system, its own RBCs and hemoglobin. So that puts increased demand of iron on a pregnant lady and thus leading to physiological state of iron deficiency anemia. So values serum iron decreases, serum ferritin that reflects actually the iron stores that also decreases because from there whatever she has stored.
It's getting transferred to the baby. So serum ion decreases, serum ferritin decreases. Because of this, the total ion binding capacity that increases.
And serum transferring increases. Even the receptor, serum transferring receptors, they increase. So please remember these changes.
Now cutaneous changes. We all know that in pregnancy, women will complain that she's having cutaneous changes, pigmentation here and there. They are because of suprarenal changes. usually begin to appear at around 4 month. The pigmentation, the common sites are linea nigra, again a sign of indication of pregnancy.
There is a line of pigmentation which appears between the umbilicus and the symphysis pubius. Linea, that is the line, it is called as linea nigra. Stryogravidarum, these are again pigmentation around the stretch marks or whatever stretching. is caused because of pregnancy there is bluish appearance they are called as striagrabudarum then increased pigmentation of the nipple primary areola and appearance of secondary areola then there can be presence of pregnancy mask many females get this on the cheek there is cloesmagrabudarum that is butterfly shaped pigmentation it can be on the forehead nose upper lip and adjoining parts of the cheeks so that gives a kind of mass capillaries called as chloesma gravidarum.
This pigmentation may persist but chloesma gravidarum usually disappears. Then there can be common complaints like excessive falling of hair, brittleness of the nails and these are because of pregnancy and related hormones. Endogamatory changes, there is vascular spider all palmar erythema which is because of increased estrogen. Hair growth, little excessive on abdomen or face, mucosal hyperpidemia and hyperpigmentation especially the linea nigra.
Sometimes there can be presence of some rashes or acne. Weight gain. Every time a woman comes to antenatal checkup, the first thing we do is we measure her weight.
Because we know that she is supposed to put on weight in pregnancy. This weight gain, if it is excessive, there is a problem. If it is less, there is a problem.
So we should know how much weight she is supposed to put on. The pregnancy is divided into three trimesters. The first three months that is up to 12 weeks is first trimester. There is no reliable data available that how much weight she should get gain in first trimester because we all know that in that trimester as soon as she gets conceived she has either nausea or vomitings and because of which she may actually lose weight rather than putting on the weight. So that change is not confirmed.
Sometimes the weight remains stable, sometimes she loses a little bit or she fails to gain any weight. So that is okay in first trimester. But in normal pregnancy, the average weight gain is around 0.3 kg per week up to 18 weeks.
Then 0.45 kg till around 80 to 28 weeks and then later around 0.36 to 0.4 kg per week until term. So if you don't remember details, just remember that around 0.4 kg she is supposed to put on per week so that we can call it as normal weight gain. What is the average weight gain?
Again MCQ. That total through 9 months, how much weight gain she is supposed to have? And the answer is around 11 to 13 kg.
Sometimes 14 kg. It is almost 1 kg less in multigravida. Prami puts a little more weight.
If she puts... puts on more weight, if the weight is gaining faster, what things would come to your mind? The first thing should come that there is abnormal water retention and that may be the cause of, the cause may be pregnancy induced hypertension.
So if patient is telling about edema, facial edema especially and excessive weight gain which we notice on measuring the weight, please rule out pregnancy induced hypertension. There are other causes but this is more important to rule out. If the weight gain is less, then what?
Then it should come to our mind whether the fetus is growing properly or not. Then intrauterine growth restriction, the first indication would be less weight gain. The weight gain is not according to what we expect.
How this weight gain is distributed? In fetus, the fetus is of around 3.5 kgs, then placenta around half a kg, amniotic fluid. almost 0.7 to 1 kg.
Uterus and breast around 2.4. Blood and the other fluids around 3.9 kgs, it's 2 kgs to 3.9. Muscle and fat and total is around I said 13 kgs, 13 to 14 kgs she puts on. Now renal system, what are the changes which are taking place in the kidney? Renin secretion, it is stimulated by progesterone.
Made by placenta, angiotensinogen and converted to angiotensin, angiotensin 1, angiotensin 2, formation of aldosterone and it adds on the distal tubule. It leads to sodium absorption, excretion of potassium and this sodium absorption leads to water retention. Almost 6 to 8 litres of water getting retained.
Renal blood flow is increased because of pregnancy. That leads to 50 to 75% increase the renal flow that leads to 50% increase of GFR, globulin filtration rate. Decreased albumin leads to lower colloid oncotic pressure. All the blood values of renal function test, serum urea, creatinine, uric acid, they all decrease. Sometimes we see glycosuria, sugar positive in urine.
And this is... Most of the times it is physiological or we can say it is glycosuria of pregnancy. But proteinuria means presence of protein in urine is not considered as normal. Glucose can be considered as normal but protein in urine is always an indication that maybe she is having PIH or some other renal pathology.
Other urinary tract changes, there would be ureteral dilatation, hydroureter. This is because of smooth muscle relaxation effect of the progesterone. There would be pressure of uterus that leads to dilatation and urinary stasis.
So a pregnant lady is more prone for urinary tract infection. Dilatation of pelvic and collisional system, renal infection, increased incidence because of again progesterone, compression and stasis and that leading to infection. So there are many other systems which have to see in details. For time being, we'll stop here and then we'll again come back and learn about other systems. Thank you.