Impact of corticosteroid-binding globulin deficiency on pregnancy and neonatal sex.

Context: Plasma corticosteroid-binding globulin (CBG) transports cortisol but high progesterone levels at the maternal-fetal interface can displace cortisol from its steroid-binding site. A secretion-deficient CBG mutant (A51V) in ∼1 of 36 Chinese causes low circulating CBG levels. Objective: Assess the implications of a CBG deficiency on pregnancy outcomes. Participants and Design: From 1978 Chinese women screened at 12–16 weeks' gestation, 50 A51V carriers were identified and 46 were followed with 60 controls throughout pregnancy. Blood samples from another 2051 pregnant women were obtained at term to determine the secondary sex ratio (SSR) of newborns in an extended cohort (n = 101) of A51V mothers. Outcome Measures and Results: Among women recruited at 12–16 weeks' gestation, serum CBG increased progressively during pregnancy but was lower (P < .0001) in heterozygous A51V carriers than controls. Two women homozygous for A51V had very low serum CBG but their pregnancies progressed normally. The A51V mo...