The levels of the maternal serum markers alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), and unconjugated oestriol (uE3) in 35 pregnant women with early second-trimester oligohydramnios differed from those in a reference population of 1699 singleton pregnancies. Maternal serum AFP levels above the 95th centile of the population distribution were observed in 80 per cent (16/20) of oligohydramnios cases with a normal fetus and in only 20 per cent (3/15) of the cases with a fetus displaying urogenital tract malformations. Elevated levels of hCG (above the 95th centile) and decreased levels of uE3 (below the fifth centile) were encountered in 26 per cent (9/35) and 17 per cent (6/35) of the women, irrespective of the fetal condition. The abnormal profile of the serum markers in early second-trimester oligohydramnios resulted in 57 per cent (20 out of 35) of screen-positive cases for either fetal Down's syndrome or neural tube defects, compared with 8·4 per cent (143 out of 1699) in the reference population.

alpha-fetoprotein, human chorionic gonadotrophin, maternal serum, Second-trimester oligohydramnios, unconjugated oestriol,
Prenatal Diagnosis
Department of Gynaecology & Obstetrics

Los, F.J, Hagenaars, A.M, Cohen-Overbeek, T.E, & Quartero, H.W.P. (1994). Maternal serum markers in second-trimester oligohydramnios. Prenatal Diagnosis, 14(7), 565–568. doi:10.1002/pd.1970140709