Dr struggling to date pregnancy after coming off the pill (question)

[busylady99]

I've read a few threads that say that if you get a BFP during your first cycle off the pill that the Dr will find it harder to date. Why is this? Assuming you have had a bleed after taking your last pill, surely you can mark the end of the previous cycle and the start of the current one. Tia

Because nobody's cycles are the same length, so people don't ovulate at the same time. If you get pg during the first cycle, there won't be a "start of the current one" ;)

I meant that the period after you have taken the last pill is the start of the cycle that you have become pregnant in :)

I understand that doctors date the pregnancy from the first day of the period. I just don't see how it is different for the doctor if it is an end of pill period or not? As cycle length can vary even in the same woman how is it more difficult when coming off the pill?

I think it's because that when you come off the pill you might ovulate very late. For example, my first real cycle was 42 days, so I probably ovulated on CD 30.

This would've messed up the LMP dating system as conception would've happened 2 weeks later than LMP would assume (on day 14). On the other side, you could ovulate very early which would also make dating less accurate.

I agree with you about cycle length varying but I suppose most people go on to resume fairly regular cycles, making only a minority of cases difficult.

Ahh that makes sense. I've been temping and charting other signs so if I did become pregnant during cycle one I'd still be able to identify when I ovulated and so when the baby was conceived. Thanks.