Related Questions

I had very irregular periods so had an ultrasound dating me at 7 weeks pregnant. Does this mean I conceived 7 weeks ago or 5? And could the ultrasound dates be wrong?

More likely 5. Pregnancies are dated from the first day of the last menstrual period, and when that date is unknown an ultrasound is the most reliable way to date a pregnancy. Even when dated by ultrasound though, the date assigned is the estimated date of conception + 2 weeks (so in your case, conception likely occurred 5 weeks ago). First trimester ultrasound is reliable to within about 5 days for dating. Read more...