The influence of gravidity on Down's syndrome screening with free beta hCG

Abstract

Total human chorionic gonadotropin (hCG) levels have been shown in one previous small study to vary with gravidity. In order to establish if maternal serum free beta hCG was similarly affected, approximately 4500 pregnancies of varying gravidity were analysed. The results indicated that there was a 6 per cent higher median MOM in primigravid compared with multigravid women. The impact of such elevation in Down's syndrome screening programmes will be minimal.