If your calculations and LMP due dates don't match..?

LargeMargeSentMe · May 2014

Based on my LMP, my due date will be December 15th, but I know for a fact that I ovulated a week later. (We only had sex once last month, so I know pretty much exactly when everything happened.) If this happened to you, did your doctor actually listen and change your due date (if their measurements matched up)? I am really worried that the doctor won't listen and will keep my due date based on LMP and that's going to drive me crazy.

LaxMOM44 · May 2014

A LOT of women on here are finding themselves in this situation which leads me to believe that the early ultrasounds/our calculations aren't necessarily accurate.

Try not to worry, I'm sure everything is fine.

merebear09 · May 2014

I was charting so I know I ovulated on CD22. My first appointment is on May 5, for a "ten week appointment" based on LMP, at which point I will be 9 weeks exactly. I'll have to wait and see what my OB says.

mc0113 · May 2014

I explained this to my doctor and she's sending me for an ultrasound next week. According to my charts and when we had sex I should be about 3-4 days later than my LMP EDD. I guess well find out how far I'm measuring next week.

chrissykzd · May 2014

my doc changed my due date after my ultrasound. based on my LMP, my due date would be 11/30. the baby measured a week behind so the PA at my OBs office said i ovulated late and changed it to 12/7, then OB changed it to 12/9 a few mins later. in my previous pregnancies, something similar has happened as well. mine always seems to go by the baby's measurements on ultrasound.

AZMagnini14 · May 2014

It really doesn't make a difference give or take one week. T hey only change it when its more than that.

caden1206 · May 2014

At first my doc doesn't listen to my dates, because my gestational sac measures bigger, but now with the baby in view he does. I am only four days of though, so really within the +/-5 days.

RayRay007 · May 2014

My MW went by my O date when I showed her my charts. If I didn't have BBT charts I'm not sure that she would have.

RayRay007 · May 2014

AZMagnini14 said:

It really doesn't make a difference give or take one week. T hey only change it when its more than that.

Well, it kind of does in the end when they want to induce you for post-dates when you aren't really post-dates yet at all.

Cheekers2010 · May 2014

RayRay007 said:

AZMagnini14 said:

It really doesn't make a difference give or take one week. T hey only change it when its more than that.

Well, it kind of does in the end when they want to induce you for post-dates when you aren't really post-dates yet at all.

This!

If they're a good doctor they'll listen. My midwife last time did. Like you, we had only DtD once that month and so there was no doubt when I conceived and that's the date we went with.

This time I knew I ovulated 4 days "late.". Fortunately the u/s agreed with my calculations to the day so my OB changed my due date to reflect reality. I would've been peeved if she didn't.

Eta: it's too early for me to make the sense

ColeyCannoli · May 2014

RayRay007 said:

AZMagnini14 said:

It really doesn't make a difference give or take one week. T hey only change it when its more than that.

Well, it kind of does in the end when they want to induce you for post-dates when you aren't really post-dates yet at all.

But by then you should have a date based on ultrasounds which would be more accurate than either estimate. Even fertilized eggs can take different numbers of days to make it to the uterus. Try asking your doctor first before assuming they want to hurt you. If they don't listen, find another.

BabyRN2009 · May 2014

Yes. By LMP I was due 11/29. But I knew I was due ~12/10 based on ovulation. Yesterday's u/s confirmed a due date of 12/11 and it was changed.

The "rule" most docs follow is that if the difference between LMP and a first tri u/s due date is less than a week (measuring ahead or beind), keep the LMP due date. If the difference is 7 days or greater, change the due date to match the u/s.

brittandjp · May 2014

My OB listens to me. If women don't know when they ovulated, he goes by LMP. However, with this being my 3rd pregnancy and I charted every time, I've always been right. I measured right on target with O, not LMP, this morning at 7w5d.

I thought this would make my EDD 12/14, but he insists it's 12/13. I'm not complaining, a 12/13/14 edd is more fun anyway.

drpayne · May 2014

AZMagnini14 said:

It really doesn't make a difference give or take one week. T hey only change it when its more than that.

It does matter when it comes to someone trying to induce you at the end of the pregnancy. You can request a dating US (I believe they're most accurate before 10 weeks? Someone correct me if I'm wrong. They're less accurate the further along you get.) Or just make sure it's noted in your chart.

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