When does the sex of the baby occur?

Answer 1

The earliest an ultrasound can possibly determine the gender of a fetus is 12 weeks. Most doctors won't attempt to determine the gender until 16-20 weeks. Unlike amniocentesis, ultrasound genderizing isn't an exact science. Depending on the way the baby lays, it can be difficult to see the genitals. Some radiologists will influence the baby to move into a different position to catch a glimpse, or you could consume something containing sugar to make the fetus more active. Amniocentesis, if you have to have one done, determines the gender through chromosomal analysis and this is fool-proof.

Other answers from contributors:

• You can probably see the sex of the fetus by three months. By then organs are already developed.

• It seems the common answer on the internet is 16-18 weeks.

• Sometimes you can tell early and sometimes you can't tell until they are born. I found out that my child was a boy at 17 weeks, but my friend didn't find out until when she had hers, and it was a girl. They had taken many ultrasounds but the baby was so lady-like she just didn't want anyone to see!

• I would agree with the last person's answer. It all depends on how modest your baby is, and how he or she likes to lay. If those legs are closed, you may be waiting until delivery! If you have a good radiologist, they may be able to coax the baby into a slightly different position. At my office (I work at an OB/GYN office), we sometimes tell moms to drink a Hi-C juice box (nothing w/ caffeine, just a little dose of sugar) to get the baby nice and active. Check with your doctor on this first, though.

• As the sexual organs are not differentiated until 16-17 weeks (before this boys and girls look the same) this is the earliest an ultrasound can tell you. Chorionic villus sampling and amniocentesis will tell you before this.

• I knew I was having a boy at 14 weeks. It's all dependent on how your baby is positioned. My sister wasn't able to tell what her first kid was because she (the fetus) had her legs crossed during the ultrasound.

• It's also a lot easier (for obvious reasons) to tell if it's a boy than if it's a girl.

• I found out that I was having a girl at 20 weeks! But it just depends on how the baby cooperates with the ultrasound tech.

Answer 2

Gender is determined the moment of conception, the male also determines the sex of the baby

Answer 3

At conception. If a Y-containing sperm fertilizes the egg, it will be a male. If an X-containing sperm fertilizes the egg, it will be a female.

Answer 4

16 wks