Amniocentesis is a chromosomal pattern test of amniotic fluid intended to identify disorders such as Down's syndrome (characteristic cleft palate) in the baby. It is done in the 15-20 week of pregnancy.
As the mother is already pregnant when this test is performed, it has no relevance to the fertility of the mother.
However, this method is being misused in India to detect the gender of the foetus which results in several female foeticides. Hence, the government has made it illegal to perform this test for sex determination.