Due Date Question

owens0410

Hoping this doesn't make me look like an idiot...but I'll ask anyways!

How many of you have went to the doctor for your first check-up and been told that your due date is different from what you thought it would be? From what I'm reading that happens pretty often? I'm just wondering how that happens. We calculate from the first day of our last period so how would that change? Are people calculating incorrectly or what? I would be so surprised if I went into the doctor's office and got a different due date.

WinchestertoPittsburgh

Depends on when you ovulated and when the fertilized egg implants and begins to grow. Not your period. Ultrasounds will correctly date the pregnancy in the end.

owens0410

Got ya. Ever since my first kiddo my period has been totally wonky. My cycle would range from 24 days to 31 days. So I have no freaking clue when I ovulated. When we were trying I was like, "Hey babe, we have an 11 day fertility window, we gotta do it every day!!" LOL! So I guess my due date may very well change!

KyCat

So I haven't had my first appointment yet, and this is my first pregnancy, but I think I can answer the general question.
The calculation of your due date from LMP assumes a 28 day cycle with ovulation on cd 14. Many women ovulate before or after cd 14. So at the first ultrasound they measure the fetus to get a more accurate gestational age, which can in turn change your due date. Also, implantation can occur from something like 6 dpo to 11 dpo, so that's another factor that can affect how developed your baby is at a certain point.

ijstarr28

Things float around for a little while. Some may implant faster than others and some may implant a little slower than others.

It's not an exact science. A few days are no big deal. 

KyCat

@WinchestertoPittsburgh you beat me to it with a much more concise answer!

oandmplus1

Pretty much what pp said.  I always just add 2 weeks to before when I know I ovulate and tell them that's when my LMP was, but this time I haven't had a period since my loss, so they are doing a dating ultrasound (although my doctor knows I track my ovulation).

joleri23

The way that my nurse explained it to me was that no one should rely on due dates anyway - most women don't give birth right on that day, so take it with a grain of salt and assume you're having a baby some time during a two week window around that time. I've always thought that was the case, so hearing her say it put my mind at ease. My technical due date as of right now is 6/29/16, but I'm just telling people July.

owens0410

I like that way of thinking of it. I am such a control freak that it is hard to think broad but you are right! My due date is July 16th so I'm telling people I'm out of comission the entire month of July and that they can find me in the swimming pool! 

owens0410

@ joleri23 Wow! When will you get to find that out?

ijstarr28

owens0410 said:

Got ya. Ever since my first kiddo my period has been totally wonky. My cycle would range from 24 days to 31 days. So I have no freaking clue when I ovulated. When we were trying I was like, "Hey babe, we have an 11 day fertility window, we gotta do it every day!!" LOL! So I guess my due date may very well change!

That sounds like fun!!!  That's basically what DH and I did too. I was only a couple days off from the LMP date when they did u/s dating. 

joleri23

owens0410 said:

@ joleri23 Wow! When will you get to find that out?

Well like I said, we know what my due date is but we also know that realistically you have no idea when the baby's going to come! I've read that statistically, most first time moms give birth 8 days after their due date... I've also read that statistically, they give birth at 39 wks and 5 days. So who knows! My body will know when it's time.

juliagulia38

I was induced with my son so he was on time according to my due date. My second one came 3 weeks before my due date. My OB thinks this baby will come anywhere from 37 weeks to 40. She expects me to deliver in June. Babies come when they want, they don't care about your due date.

stillcozy

Hi I just had this happen on Monday. So the first day of my last period was 9/18 which put me at a June 25th due date but Wee little baby is a week behind that measuring to come a 7/4/16. The reason for mine is I ovulated later this is most likely because I had an irregular period before I had gone on the pill and I got pregnant my first month off of it so my body was just still adjusting. it's not a bad thing but everyone's body just works a little different