Expert: Dorothy H, LCCE - 3/24/2010

Question
Dorothy,

I am currently pregnant and ultimately trying to figure out when I conceived my child.  My due date is August 26.  My last menstrual period came around November 23-30 and I typically have a 27-28 day cycle that occurred normally each month before I became pregnant.  After my current boyfriend and I broke up I had sex with my ex boyfriend on November 14.  My current boyfriend and I got back together and had unprotected sex soon after my November period ended.  I did not have a period in December.  

I know that I am not providing you with exacts dates as to when my period occurred of as to when I had unprotected sex with my boyfriend, however, I need to try to figure out if my current boyfriend is the father of my baby.  As I mentioned, I did have a full period (vs. spotting) after having sex with my ex boyfriend, however, I have read that a woman can still have a period after conception if she conceives late in her cycle.  My concern is that I conceived late in my cycle before my period came at the end of November (which would mean that I conceived when I had sex with my ex boyfriend on November 14).  

I am extremely embarrassed to be in this situation, but, I need some guidance as to whether my ex boyfriend or my current boyfriend is most likely to be the father of my child.  Thanks.

Answer
Hi Ashley,

Looking at your due date, I see that it does not line up exactly with your LMP, which indicates to me that you probably had an ultrasound to determine your due date.

Going by your dates, it looks like you conceived around December 2.  If you had an ultrasound to confirm your dates, there is no way that your ex-boyfriend is the father of your child.

If you did not have an ultrasound, I would suggest getting one to put your mind at ease. An ultrasound can be off by a couple of days, but it won't be off by several weeks.

Sincerely,

Dorothy H.