Usually you have an ultrasound in between 18-22wks. They can usually tell you the sex if you want to know.. But not always. It's all up to the baby. Sometimes they don't cooperate.

Beginning at 18 weeks...

No it really depends actually. Usually with a boy you can tell earlier-some people at 14 weeks knew what they were having.

I found out only at 19 weeks cause that's when I had my next u/s after my 12 week one.

.U.S.U.A.L.L.Y it's anywhere from 16 weeks on.

Yeah you can try earlier but its less accurate. My cousin found out it was a boy with little certainty at 13 weeks.....Boy bits are easier to detect for obvious reasons! Lol

Us tech told me the most accurate reading begins at 18 but sometimes you can tell earlier.

The u/s tech told me it was a girl at about 15 weeks and she was right! But usually they do one 18-22 weeks and they are more accurate.

I found out at 18 weeks that I was having a boy, but I had a 3d ultrasound because where I live they wont tell you the sex in regular ultrasounds