Expert: Dana Krempels, Ph.D. - 1/9/2009

Question
can the genotype of an unborn child be determined?if yes,at what maturity of the pregnancy

Answer
Dear Udoka,

If you mean the genotype for a particular trait, then whether it can be determined before birth would depend on the specific trait you're interested in knowing.  Some can be determined, and some cannot.

Several different types of prenatal genetic testing are available, and each has its particular risks and benefits.  

In amniocentesis, a sample of amniotic fluid is taken. This usually contains sloughed skin cells from the child.  These can be cultured, the
chromosomes analyzed, and--if necessary--the DNA amplified and analyzed.  

Chorionic villus sampling is a somewhat more invasive procedure that can be done a bit earlier than amniocentesis, but it's also more risky.

You can read more about these two techniques, their timing, and the relative risks and benefits of each here:

http://wonder.cdc.gov/wonder/PrevGuid/m0038393/m0038393.asp

I hope this helps.

Dana