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How to find out your due date?

Shieva Ghofrany: [00:00:00] Good morning. It's a terrible rainy day here in Connecticut on a Thursday, but I'm gonna go deliver a baby. Let's go make it more fun. And this delightful baby. Let me sleep all night long, which is fabulous. So it made me think of. an issue that I think a lot of you guys are confused about cuz we're confused about it sometimes too. 

So a couple things. Let's talk about how we date the pregnancy. Meaning how do we find out your due date? Um, and my conundrum and annoyance, which is, why do we say pregnancy is nine months? And I don't have a good answer for that, but I will give you my thoughts. So first of all, just to give you the low down, you will always be asked when your last period is because pregnancy is. 

by 40 weeks from your L M p last menstrual period. So you'll see that a lot L M P last menstrual period 40 weeks later, which is 280 days is considered your eed c estimated date of confinement, which is sold fashioned cuz we are no longer confined. Um, sometimes we wish we could be for rests sake or your e d d [00:01:00] estimated date of delivery, which is much more modern, but somehow many of us still use edc, so, Lmp, your last Metrol period, which is the first day of your last period, not the last day. 

The first day of your last period, 40 weeks later, is your due date. Now babies do not often come on their due date. In fact, many babies don't. In fact, most babies don't. There's a span and you're considered full term. Anywhere from 37 to 41 weeks. Um, post dates is considered after 41 weeks, meaning seven days past your due date, though many of us, you know, there's a back and forth as to whether or not you should be allowed to go past your due date. 

We're not gonna talk about that right now. We're gonna talk about how accurate is it to use your last period. Well, in women who have a 28 day cycle, it's actually very accurate because 14 days before your next period you would ovulate. You might remember one of my last videos about ovulation. But in a 28 day cycle, it happens also be 14 days after your first day of your period. 

So if you have a 28 day cycle, you go [00:02:00] into your doctor anywhere from six to eight weeks, ideally closer to eight weeks. But sometimes patients come in early, um, you tell them your, your period. They have their wheel. We look on that pregnancy wheel. It's so archaic, but we love it. It tells us, okay, you're, let's say, you know, seven weeks and five days pregnant, let's do an ultrasound. 

Again, I'm not saying everybody does it, but many places will do a transvaginal ultrasound to date the pregnancy and confirm the heartbeat and confirm the due date, cuz it's the most accurate time to do it because you'll see that little bean, I call it a little grain of rice and we. The crown to the rump, and that's one single measurement, which means the likelihood of an error is much less than when the baby gets bigger. 

So assuming that the due date matches what we would've calculated with your period within five to seven days, depending on who you listen to, then we keep your due date. In other words, if my due date says you're seven weeks and three days, and your due date said you're seven weeks and five days, I should not change the due.[00:03:00]  

If you have a 28 day cycle, if you happen to know that you're always at 32 days, for example, then we can alter the due date a little bit. Okay. Let's say it's more than seven days off from your period, then we are supposed to change the due date, even though you might say, but my period is always 28 days, and I might say back, I get it, but data has been showing. 

That women up to 25% of the time, even when they know their cycle, their pregnancy actually occurred at a date that was different. And that can be for various reasons. One is even if you have a regular cycle, any particular cycle can be off by a couple days. Two is that sperm and eggs can last probably longer than the requisite. 

What we say like, oh, it'll last a day or two. We've had patients who swear by when they had sex and their pregnancy is dated and consistently stays a different. Okay, so you tell us your last menstrual period. We do an ultrasound to confirm sometimes we change the date. Once you've changed the date in that first trimester, assuming it's good ultrasound and good. 

[00:04:00] Practitioner who's used to it, you really shouldn't then change the date later. Because once you get to, let's say 28 weeks and the baby's big, and patients will say, does that change my due date? The resounding answer should be no, because you might mistakenly be saying, oh, look, this baby is older. Let's change your due date because the baby's this big. 

When in reality it's just that the baby's big. So once you get past that first trim, The error in the measurements of the machine, its ability to actually measure weight accurately is off by 20%, even in the best practitioners the data has shown. But again, babies will diverge in their weights somewhere in that 20, 24 week span. 

So you cannot say that a big baby at 28 weeks is actually has a different due date. So do not change the due date because then you might be prematurely delivering babies or going far past your due date in a way that you shouldn't be. Okay. Now let's get to this 40 week thing, cuz it bugs me because I feel like, I know I'm, I'm being all like angry, matriarchal. 

But is it the [00:05:00] patriarchy trying to like claim you're only pregnant for nine months because ladies, The last time I checked four months. I mean, each month is four weeks, right? Yes. I know some months are 30 or 31 days. But then why do we say, okay, pregnancy is 40 weeks, which when you divide it by four, should equal 10 40 divided by four. 

We are actually pregnant for. 10 months. When you think about it, it sounds nitpicky, but if you're that lady who's holding that baby and you're exhausted and people are like, oh, you're only pregnant for nine months, it's annoying. That said, there's actually clinical implications, I think, and here's an example. 

Well, first of all, let me just tell you, like while I was researching this, I actually realized, I think the reason why people say nine months is because they used to say full term is 37. . Now full term is still 37 weeks. Technically, if you go into labor on your own, we won't label it as preterm at 37 weeks, but they're starting to change the vernacular a little bit. 

And we realized that certainly electively, we should not take a baby out until 39 [00:06:00] weeks. So maybe the 37 weeks was what they used to say full term. And maybe that's why they say nine months. I don't know. To further make it interesting, my mother, who's a pediatrician, retired and did her medical school in Iran and grew up there, said they used to calculate and they used to say that someone is actually pregnant. 

Nine months and nine days, which still does not get you to 280 days, but definitely makes you closer, at least booya for the Iranians. Here's where I think there's clinical implications. I will have patients who come in with their second pregnancy. The first was not with us, let's say, and they'll say, oh, I delivered early. 

Oh, okay. Tell me why and when, because it does have implications for us. Did you deliver early because they induced you because of preterm, um, because you had an infection, because you had pre-eclampsia? Did you go into spontaneous labor? Did your water break? Like these all have implications for your next pregnancy as to what we may do. 

To alter the likelihood of a preterm delivery again. So this is how it'll go. Oh, I delivered early. I delivered at [00:07:00] eight months. Now to the average person, eight months means how many weeks? I'm assuming you're all saying 32 weeks. Right? But eight months in pregnancy terms to the late person. probably means one month earlier than nine months, meaning one month earlier than your due date, which would mean 36 weeks. 

And there is a big difference for us in a preterm delivery at 32 weeks versus a preterm delivery at 36 weeks. And there may even be a difference with regard to how aggress. We manage the patient in the next pregnancy. So outside of my annoyance, because people should respect the fact that we are gestating and growing humans for 10 months, it actually has clinical implications. 

So I wish the powers that be, which I wouldn't even know who's gonna change this, but I wish they would change it. So I hope that's helped. Oh, we didn't talk about this. What if my period is irregular? Why don't they define pregnancy as, um, instead of 40 weeks from your period? 38 weeks from when you ovulated, which is actually much more accurate as far as.[00:08:00]  

how long pregnancy should be. But as you guys might know from trying to get pregnant, pinpointing ovulation is very hard. You can try the ovulation kits, but they're not always so accurate and they're frustrating to use. There's no single blood test that for sure will tell me, oh, that you did ovulate. 

There are some, but it's not ideal. It's seven days after you think you've ovulated. It's progesterone. It's not a great test. So again, there's just no way. So for, but the standard is, okay, let's pick someone's period. Many women don't know their period or have very irregular period. Or have never had a period, but you can still ovulate cuz you ovulate before you bleed. 

So lack of a period does not mean you didn't ovulate. So once you find out you're pregnant, if you have no idea how far you are, you could always go see the doctor early enough because at least with an ultrasound, they'll be able to tell you. Okay, that's it. I'm gonna stop ranting. I'm gonna go deliver baby on this rainy day. 

Hope you all have a good day. Bye.