MATERNAL SERUM MARKERS IN 2ND-TRIMESTER OLIGOHYDRAMNIOS

The levels of the maternal serum markers alpha-fetoprotein (AFP), huma n chorionic gonadotrophin (hCG), and unconjugated oestriol (uE3) in 35 pregnant women with early second-trimester oligohydramnios differed f rom those in a reference population of 1699 singleton pregnancies. Mat ernal serum AFP levels above the 95th centile of the population distri bution were observed in 80 per cent (16/20) of oligohydramnios cases w ith a normal fetus and in only 20 per cent (3/15) of the cases with a fetus displaying urogenital tract malformations. Elevated levels of hC G (above the 95th centile) and decreased levels of uE3 (below the fift h centile) were encountered in 26 per cent (9/35) and 17 per cent (6/3 5) of the women, irrespective of the fetal condition. The abnormal pro file of the serum markers in early second-trimester oligohydramnios re sulted in 57 per cent (20 out of 35) of screen-positive cases for eith er fetal Down's syndrome or neural tube defects, compared with 8.4 per cent (143 out of 1699) in the reference population.