Screening for Down's Syndrome with Dimeric Inhibin A

Biochemical markers including alpha-fetoprotein, the β subunit of human chorionic gonadotropin (hCG), and intact hCG are used to screen for Down's syndrome in the second trimester of pregnancy. This study assessed the added value of measuring dimeric inhibin A.

Serum samples from 528 women between 7 and 18 weeks' gestation were obtained from a prenatal screening service. Fifty-eight fetuses had Down's, 32 had trisomy 18, and the rest were normal. Serum concentrations of inhibin A in Down's pregnancies were 2.06 times the median value seen in normal pregnancies, versus 2.00 and 1.82 times the median for the β subunit of hCG and intact hCG, respectively (all findings p<0.001). Inhibin A levels were not elevated until the second trimester. The …