MATERNAL SERUM INHIBIN LEVELS IN 2ND-TRIMESTER DOWNS-SYNDROME PREGNANCIES

Maternal serum inhibin levels were measured in 19 second-trimester pre gnancies affected by fetal Down's syndrome and 95 unaffected control p regnancies matched for gestational age. A statistically significant el evation was found in the affected pregnancies compared with the contro ls (Wilcoxon rank sum test: one-tail P=0.02). The median level in the cases was 1.3 times that in the controls, with 95 per cent confidence limits of 0.9-1.9. Although the inhibin levels were unrelated to those of alpha-fetoprotein and unconjugated oestriol in the same samples, t here was a statistically significant correlation with human chorionic gonadotropin. This together with the relatively small elevation in cas es suggests that inhibin would be of limited value in maternal serum s creening for Down's syndrome.