How did your doc calculate due date?

jr63_2020 · July 2010

I am still looking for an ObGyn (it's only been 2 days). Still, I spoke to my Gyn on the phone, and she calculated my due date by the first day of my last period. My physician calculated it by the day I think I ovulated. I'd think the day I ovulated would be more accurate, but is this what the rest of the world uses? How did your doctor calculate your due date?

anna2029 · July 2010

Based on my last period

staycee · July 2010

I charted so I knew my O date.

U/S confirms that.

if I went by my LMP - I'd be a week and a half further along.

papagena · July 2010

Most doctors in the US go by LMP (Last Menstrual Period), primarily because not all women really know when they ovulated, and 'generally' speaking, women ovulate about 2 weeks after their period starts (obviously that varies).

If you truly know when you ovluated (were temping, etc), that will be more accurate. However, they add 2 weeks to the LMP date, so if you have 'average' cycles, the dates probably won't be that far off. For people with long or not regular cycles, obviously LMP dates can be way off.

Our doctor checks with an early u/s to get an accurate date of pregnancy. Mine was within 3 days of the LMP date, so they let me keep the later date (whoot).

mlkbride03 · July 2010

Based on last period and confirmed with u/s.

vflipo · July 2010

Based on my LMP. I know I ovulated later in my cycle, based on that my EDD is Feb 22. So far, baby has measured right on for the LMP EDD (Feb 18). Weird.

CutieBean79 · July 2010

first day of last period. He'll do an ultrasound at 8w3d to check up on things and verify the due date.

RayRay007 · July 2010

Well I told my GP I knew when I ovulated, so he calculated based on that, but then asked me when my LMP was and calculated a different date based on that, and used that date on my BW forms saying it was convention. It's like 5 days off. My ticker is based on O date, and when I go to my midwife in late Aug., I'll see what she uses.

niceybee05 · July 2010

Dr. did LMP 4/1/11 but based on my ovulation it is 4/6/11. Since it is only a few days they will go with LMP until the ultrasound.

sparkelz · July 2010

My doctor uses LMP as a standard to calculate due dates and he will do an early US to confirm. In my case the ultra sound showed that I was a week behind what my LMP was showing so he moved my due date back by a week as a result of the untra sound.

KamMitchy · July 2010

By an u/s b/c my periods are whacky

babyblues314 · July 2010

He used my LMP because I wasn't charting that month so don't know when I O, but he did an ultrasound and said will change my due date based on that. Right now it 2/19/11, but I KNOW I'm not that far along...thinking more like end of Feb beginning of March....will find out in 2 weeks!

PinkLove-S · July 2010

Going by your O date is more accurate if you don't O on CD14 but i really don't think a doctor can go by a date you **think** you ovulated. Either you know or don't. If you don't then over the phone they go by your LMP as a standard practice until you get in for a u/s they can date you for.

Beccaboo0713 · July 2010

Via ultrasound.

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