Guy A or Guy B?

[Parsnip10]

To cut directly to the topic, my LMP was April 9th. I slept with Guy A on 4/12 (cd4), 4/16 (cd8), and 4/25 (cd17). I slept with Guy B once on 4/18 (cd10). I usually have 29 day cycles. I explained everything to my OB and he said the ultrasound will be able to tell within 5 days of conception. I will have one done in a week and I will be 8 weeks. Any idea of which is most likely the father? My doc thinks guy A but a lot is depending on this and I am a nervous wreck. Thanks for any input...

[AnnieBrooke]

I'd see if you can get in on a cancellation and get an ultrasound this week, not next week.  If your cycles are always and invariably 29 days long (or, if your new period always begins on the 29th day after the last one does) you can be expected to have ovulated on April 24.  But if they are not invariable and not like clockwork, you really have a toss-up.  That's why an ultrasound in the 7th week will be more helpful than in the 8th week. The margin for error begins to come into play after a while and it gets bigger as the pregnancy progresses.  (By your 12th week, the doctor will say "plus or minus 7 days" when giving you an estimated conception date from an ultrasound.)  But in your 7th week the measurements can be spot-on.

The other option is to get a prenatal DNA test from Ravgen or the DDC.  It costs, but then you would know.  If you go that route, test with both men.