Amniotic fluid samples
were collected for analysis from 317 consecutive women who
underwent a transabdominal amniocentesis at weeks 15–17 of
pregnancy and were stored at 80C. Indications for amniocentesis
were advanced maternal age, family history of chromosomal
abnormality, maternal request, or positive detection
on “triple test” for alpha fetoprotein, estriol, and beta human
chorionic gonadotropin