Confused

[LoveLetters]

I only had sex twice in a month. Two days in a row when I was ovulating. Planned :) do I count from first day of last period which would make me 5 weeks or when I know I became pregnant which would make me 3 1/2 weeks. Pls help!

[SaulGood]

Traditionally pregnancy is dated from 2 weeks before you conceived. In the average woman this is the first day of her last menstrual period.

It's because back before scans and a real intimate working knowledge of conception and pregnancy, it was known that a pregnancy seemed to last around 40 weeks from the last period. We know now that actually it's an average of 38 weeks from conception but we still date things that way until the scan gives a better idea of when a woman conceived. Two women can have a period start on the same day and one ovulate on day 9 and another on day 29. That's almost a 3 week difference but if you dated from lmp, they'd have the same due date.

So basically, if you know when you conceived, add on 2 weeks. That will give you a rough idea for now and when they scan you, they'll work from actual measurements.