I am 29 weeks pregnant, my due date is October 10, 2010. My last menstral period was Jan 6-Jan 10. I went to the doctor on Feb. 22, and she said I was 7 weeks pregnant. I had been with my boyfriend for three years, and had sex very frequently. We had sex Jan 1, 3, 8, 9, 10, 11, 12, 13th. (I was on my period a couple times we had sex.) We broke up, and I had sex with someone else around Jan. 20th. I asked my doctor if she was sure about the 7 weeks, and she said yes, even though my period was not over until the 10th. I went to the doctor for an ultra sound around 21 weeks and the baby weighed about 1.3 lbs, and my due date has not changed. I just want some assurance, or some opinions on who the father would be. I know it is close to time, but I really believe and according to the doctor my first partner would be the father. I do not think that doctors could be that far off, because I thought it took about 10-14 days after sex to become pregnant, which if I went to the doctor feb. 22, and the doctor said I'm 7 weeks, there isn't a way it could be the second partners. Right? I'm just afraid. Any help would be appreciated.

Your due date is going from the first day of your last period. This is only a guide however... and anywhere from a couple of weeks before or after is a perfectly normal delivery time.

When you got pregnant depends on when you ovulated... which is roughly about 12-16 days before the next period would be due. This is different for different women however as some ovulate a bit sooner, some a bit later. The only time you can get pregnant is if you happen to be close to ovulation when you had sex. If you are ovulating at that time (the egg is only viable for about 24 hours) then conception happens in hours not days.

Because your dates are so close, it really can go either way. The sex on the 20th puts you about midway through a cycle (if your cycles are around 28 days), which can very well be when you ovulate.

The 7 weeks was the gestational age... time from the first day of your last period. But few women are actually pregnant in the first week or two with gestational age... hence the range of normal delivery time at the end of pregnancy. If you ovulated early... it would be your boyfriend's. If you ovulated around midcycle, it could very well be the other man's.

To know for sure... have DNA testing done after baby is born.