Cycle/dating question

jaclynne

I just have a somewhat random question. My apologies if this is not the right place to post it. My H and I have been trying for 6 months and I am currently in the TWW now and we were debating about something and I'm wondering if you ladies might know the answer. Just for an example, if two women both start their period on the same day, but have different cycle lengths and one ovulates on day 14 and one ovulates on day 21, if they both get pregnant that cycle, are their pregnancies both still dated at the same time (because they usually date it from the first day of your last period)? Wouldn't one baby be approximately a week older gestationally than the other and wouldn't that confuse an early ultrasound's measurements, scaring the mom-to-be? Please excuse my ignorance if this is a dumb question. Thank you.

dmsmth

Yes,yes and yes. So if you are charting and know you o'd late or early you should tell your dr

spiltmilkz

If you know the exact date of ovulation by charting, my ob would consider that the starting point for calculating the due date. I don't know if all ob's are the same with that but I have long cycles so if I went by last menstrual cycle they could put me at two weeks further along than I would be.

jaclynne

Thank you so much for your very helpful replies!

[Deleted User]

The user and all related content has been deleted.

[Deleted User]

The user and all related content has been deleted.

tlc35

MoonandBack141 said:

Can I ask a spin off question here-- When people say they are X weeks pregnant, are they going off of their LMP date or their O date? So for example if they say 13 weeks is the end of the first trimester, should someone be counting 13 weeks from their LMP or 13 weeks from their O? And when they say a person is typically pregnant for 40 weeks does that include the weeks between LMP and O (typically 2)?

Yes, the way we date pregnancies is from the first day of LMP so you are correct.  It is a bit of a crappy way of dating and referencing dates for exactly the reasons that you and OP noted.