DECREASED ALPHA-FETOPROTEIN IN AMNIOTIC-FLUID AND MATERNAL SERUM IN DIABETIC PREGNANCY

Objective: To determine a reference level for alpha-fetoprotein (AFP) in the amniotic fluid (AF) in pregnant women with insulin-dependent di abetes mellitus in order to suggest an explanation for the observed de crease in maternal serum AFP. Methods: Alpha-fetoprotein was measured in AF, maternal serum, or both in the second trimester in 287 pregnant women with insulin-dependent diabetes mellitus. Retrospectively, thes e AFP values were correlated with glycosylated hemoglobin (HbA1C) leve ls, early fetal growth delay, and congenital malformations. Results: T he median concentration of AFAFP was 0.89 multiples of the normative m edian (MoM) (n = 280; 95% confidence interval [CI] 0.88-0.93 MoM); the maternal serum AFP (MSAFP) value was 0.78 MoM (n = 155; 95% CI 0.77-0 .84 MoM). A statistically significant but weak positive correlation wa s found between HbA1C and MSAFP (r2 = 0.033, P = .03), but the correla tion with AFAFP was not statistically significant. The levels of AFP d id not correlate with early fetal growth delay. One neural tube defect , but none of the 11 other major malformations, was detected by AFP sc reening. Conclusions: A physiologic basis for the decreased AFAFP and MSAFP levels is still obscure. Screening for congenital malformations in diabetic pregnancies should include both a mid-gestation ultrasound scan and MSAFP measurement. However, routine amniocentesis does not s eem to be indicated. Concentrations of AFAFP may be corrected for the observed decrease.