maternal serum human chorionic gonadotropin ( hcg ) and the free alpha-hcg subunit were evaluated in 249 women from 9 to 11 weeks gestation who subsequently underwent chorionic villus sampling for determination of fetal karyotype and in 20 women of 18 or more weeks gestation who were ascertained to have an aneuploid fetus by genetic amniocentesis .
C0017963
alpha
C0018062
hcg