How is the sex of a fetus determined?
There are a few ways. The traditional way is to do an amniocentesis in which
the doctor inserts a long needle through the mother's abdomen and removes
some of the fluid from the womb. The baby sheds skin cells each day just as
we do. Each cell contains 46 chromosomes and they can be arranged in pairs in
a picture. They can then be examined for any defects, etc. The sex
chromosomes can also be viewed at this time and if it is a boy it will have
an X and a Y. If it is a girl, it will 2 X's. Ultrasound can also be done
and if the baby is oriented in the proper way, sometimes the gonads are
visible. This method is not foolproof however.
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Update: June 2012