hey everyone it's sarth register nurse rn.com and in this video I'm going to be going over nagle's rule this video is part of an inlex review series over maternity nursing so if you're studying maternity be sure to check out the other videos in my playlist and as always in the YouTube description below you can access the free quiz that goes along with this lecture which will test you on calculating nagle's rule so let's get started first let's start out talking about what is nagle's Rule Nagle rule is a calculation used for estimating the due date of a baby and it's based on a woman's last menstrual period now this calculation that you get with Nagel's rule is an estimation because it bases its calculation that the woman has a 28 day cycle which many women vary on their cycle length and the typical gestation period of 280 days which is 40 weeks and we know that um a lot of times firsttime mothers can go over that 40 weeks so this number is just an estimation now one thing you want to keep um in the back of your mind while you're calculating Nagel's rule is that you need to remember the months that have 30 days versus 31 days and of course February you will always give it 28 days regardless of a of if a leap year is that year just to keep things simple so to help you remember which months have 30 versus 31 I recommend remembering the pneumonic that maybe you were taught as a child um that that goes as the following 30 days half September April June and November all the rest have 31 except February alone so those months that have 30 days September April June and November and all the rests have 31 now let's look at those calculation formulas that um you need to remember when calculating Nagel rule there's two of them um the first one you can use where you can have the last menstrual period of the woman and you will subtract 3 months from that add seven days to the last menstral period and then add one year and then you'll get your estimated due date or you can use this you can add 7 days to the last menstrual period and then add nine months and that'll give you the estimated due date now the thing with these is that as you can see here if your woman's last menstrual period was January through March it's best to use this calculation to keep things simple compared to this one because for instance um if the woman's last menstrual period was in January we just know nine months from January will be calculating out she'll be having it within that same year however if you're not paying attention and you're using this one you'll add a year to it putting it in the next year and you know on tests that they will have both options so you don't want to select the wrong ones so just to help keep you straight and keep things simple if the last menstrual period is January through March use this one if the last menstrual period is April through December use this one now let's work a problem I going to work two I going to work one that's relatively easy then I want to work a tricky one after this and see if you um know how to work it so if you want just work these along with me okay we're given a scenario a lot of times the question's going to say patients at her prenatal visit and um think she may be pregnant or she is pregnant and she says that her last menstrual period was September 2nd 2016 using nagle's rule when is the estimated due date okay so September 2nd 2016 Falls within April to December so let's use this calculation so what we're going to do is we're going to subtract three months through September so I just this is how I like to do it to keep things straight so we're going to subtract 3 months and that's going to give us June 2 2016 then we're going to add seven days to this so we're going to add seven days and that's going to give us June 9th 2016 then we're going to add a year and that's going to give us June 9th 2017 so that is our estimated due date for a woman who had a last minstral period on September 2nd 2016 now let's look at the tricky one okay the last minstral period was September 28th 2016 so it falls within the April to December range so it's we use this calculation so what we'll do is we'll subtract 3 months from September 28th and three months from September is June so June 28th 206 now we're going to add seven days and this is where your little pneumonic comes in because remember in June there is only 30 days so 7 days out from June 28 would put us in the next month which would be July 5th 2016 now we need to add a year and that will put us at July 5th 2017 so our estimated due date is July July 5th 2017 now let me just show you if you use this one instead why it would throw it off let me erase this okay so say you did this instead um wanted to use this one so what you would do you would add seven days to September and you know that there's only 30 days in September so that would put us at October 5th 2016 then we would count 9 months okay well 9 months out from October is July so it would be July 5th and a lot of people don't remember to flip it over to the next year so they might end up putting just 2016 instead of adding 2017 so that's where if you're comfortable and you'll remember to add that extra year then of course you whatever calculation you want but if you're like me and you need to keep things straight um just remember this calculation is best for that that month those months January through March and this calculation is best April through December because like I said if you use that calculation on that you may put your answers July 5th 2016 when it should be July 5th 2017 okay so that is about nagle's Rule now go to my website register nurse rn.com and um work some practice questions to see how well you grasp this material and don't forget to check out my other videos and please consider subscribing to this YouTube channel