How do they determine a baby's sex before birth?

looney_tunes

Amniocentesis, a process involving extraction of amniotic fluid (which contains fetal cells) from within the amniotic sac, can provide material for a number of tests on the genetic makeup of a fetus. Gender is one of the simplest of these. The test is usually performed as a check for various genetic defects (such as Down syndrome), and the determination of gender is a collateral observation. http://en.wikipedia.org/wiki/Amniocentesis Mar 30 11, 2:19 AM

Watchkeeper

More simply, from the regular ultrasound scan at about 20 weeks gestation, when the ultrasonologist looks for the relevant bits (!). It's not guaranteed and the baby may not co-operate. This is the case with my imminently-expected grandchild, whose sex remains a mystery to us. And thank you, star_gazer, for correctly using the word "sex" rather than that abomination "gender". http://pregnancy.about.com/od/boyorgirl/ss/genderus.htm Mar 30 11, 5:03 AM

Zbeckabee

The prenatal gender testing has proven itself best to identify whether a mother is carrying a male child or female. The presence of X chromosome in the blood sample collected from mother indicates that she is carrying a female baby whereas the presence of fetal Y Chromosome indicates that she is carrying a male baby. The gender of the fetus can be ascertained accurately after more or less than seven weeks of pregnancy. During this period of pregnancy, the fetal DNA is sufficiently found in the mother's blood. Thus, identifying the fetus' gender through prenatal gender testing is easier. http://lawyers-law.com/boy-or-girl-what-prenatal-gender-testing-can-help-in-identifying-the-sex-of-the-unborn/ Mar 30 11, 9:17 AM