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2 Bumps

Why is pregnancy counted starting from the first day of your last period? Why don't they count it from ovulation or conception?

Answer Question

Asked by Anonymous at 7:07 PM on Sep. 15, 2010 in Pregnancy

Answers (8)
  • I have no idea but that would seem to make more since wouldn't it.

    Answer by But_Mommie at 7:08 PM on Sep. 15, 2010

  • Technically you can it is just not as many days. The reason they go by your period is because most women know that date...not everyone can be 100% sure when they ovulated or conceived.

    Answer by rlhall1980 at 7:11 PM on Sep. 15, 2010

  • IDK. I thought that was dumb too. But I guess most people can't point out the exact day conception happened. I did so I set my own due date.

    Answer by jus1jess at 7:11 PM on Sep. 15, 2010

  • Although the estimated day of conception is literally the day you first become pregnant, most people don't count pregnancy from that date. That's because there's no way to know for sure which day you really did ovulate and conceive.

    So most health professionals take the easier route and go back to the first day of your last menstrual period – a date that more women can pinpoint for certain. Then they count forward 40 weeks from that day to find your due date. (On the other hand, if you count your pregnancy from your estimated date of conception, your due date will be only 38 weeks from that day.)

    Answer by BradenIsMySon at 7:11 PM on Sep. 15, 2010

  • Because they are more likely to know when the first day of your last period was than when you ovulated, since ovulation is not usually noticed nor kept track of by most women AND everyone ovulates a different number of days after their last period. So they call 40 weeks from the first day of your last period 'full-term', when really gestation is approximately 38 weeks long. But even those estimates of how far along the pregnancy is can be pretty off because many women don't ovulate exactly two weeks after their period. So that's why it's kind of silly to put a lot of stock on one's due date. It's very very variable and yet they use a generic formula to estimate it.

    Answer by katinthehat8914 at 7:12 PM on Sep. 15, 2010

  • My doctor actually has counted from conception for me but that was because my last three periods before i got pregnant weren't really normal periods. And I also had an ultrasound at 6 weeks to know the correct conception date and due date. I have also had numerous ultrasounds to keep track of size of baby and due date has not changed and I am in my 33rd week.

    Answer by Congenial at 7:20 PM on Sep. 15, 2010

  • While most people don't ovulate on the same day, I think it's safe to say almost no one has concieved on the first day of their last period. Maybe a few cases but almost everyone ovulates before or after they're period not during. Anyway that's why I hate when people ask my due date and expect me to say an exact day the Dr doesn't know it's just an educated guess. This time I actually know the exact day of conception ( I happened to be tracking it as a method of birth control-ha ha) and my due date is still off! It's a week early so I'm just telling everyone I'm due at the end of march.

    Answer by ainstalshia at 7:29 PM on Sep. 15, 2010

  • I was told to count 7 days after my last period....9 months after the period plus 7 days ,in other words. It worked. I had a period on May 7th and nine months later, my baby was born on Feb 14th.

    Answer by gertie41 at 11:29 PM on Sep. 15, 2010

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