Conception dating

Can You Date Conception From Ultrasound Data?

Jane Foley's picture


Hi Ms. Ultrasound,

I hope you can help me with my question as it would really ease my concern.

I am 31 weeks pregnant; the first day of my last menstrual period date was 26 July 26, 2009 and my usual length of menstrual cycle ranges between 28 to 30 days.

I had unprotected sex on August 6th (Day 12) and August 17th (Day 23). I really need to know whether the baby was conceived on the 6th, or the 17th.

Here are the information of my early fetal ultrasounds: