When Did I conceive

I had an ultrasound the 12th, I was four weeks but according to what i told them my period was last month on the 8th i would have been 5 weeks. so how far am I? Do they tell me how many weeks I am pregnant or according to the ultrasounds. Do i forget about my period and go off the four weeks, being 2 weeks I conceived? I had intercourse the 17th and the 23rd when did I conceive from?

[AnnieBrooke]

If you are told by a doctor that you are four weeks pregnant because of what the ultrasound shows, it means the ultrasound did not show much.  I've heard that the only thing an ultrasound can see at 4 weeks (counted the medical way, from the beginning of the previous period) is a slight thickening of the uterine lining.  If your period began on the 8th of June and you had an ultrasound on July 12, you'd be 4 weeks, 6 days, the way the doctors count.  If the doc said you were 4 weeks even, he is probably saying not much was seen (no sac, and so forth), which means you might have ovulated just a little later in your cycle.  In that case, I'd take the 4 weeks figure as the one to trust.

People often write in with this question if it is a matter of two candidates as the dad.  If that is why you want to know, six days' difference is not enough to be sure it is one or the other, especially since by some research, sperm can live that long in your system.  If that is the case, a DNA test after the baby is born is called for.

[nicole22435]

Thanks so much! I think I ovulated late. Because id be four weeks if i conceived on the 29th bbut that would have mean the sperm survived 6 days but if the 2 weeks are added on from my period but it would have meant my period started on the 15th so idk. they say go by the ultrasound than period and that the ultrasounds at 4 weeks is the baby at 2 weeks. Thank you for your help.