A reassessment of maternal serum alpha-fetoprotein in diabetic pregnancy.

We assessed maternal serum alpha-fetoprotein (AFP) concentrations in 227 diabetic women who belonged to different groups of White's classification but found no difference either between the insulin-dependent and the normative population or between the former and diabetics who were not insulin-dependent. By contrast, we found in maternal blood a marked, statistically significant inverse correlation between maternal serum AFP and the concentration of glycosylated hemoglobin in maternal blood assayed within 6 weeks of each other in mid-gestation (r = -0.4, p less than 0.05), but not when glycosylated hemoglobin was determined in the first two months of pregnancy (r = 0.05). These data indicate that the decrease in maternal serum AFP found in pregnant diabetic women is related to the efficacy of diabetic control but not to the diabetic status. A correction in maternal serum AFP should therefore be applied only to values obtained for women with poor glycemic control. Decreased maternal serum AFP in poorly controlled diabetics may indicate reduced synthesis of other fetal proteins which, in turn, may correlate with fetal growth retardation and the occurrence of malformation.