High maternal levels of hemoglobin A1c associated with delayed fetal lung maturation in insulin-dependent diabetic pregnancies

Phosphatidylglycerol (PG) in 227 amniotic fluid specimens obtained by amniocentesis during the third trimester and hemoglobin A1c (Hb A1c) in 889 maternal blood specimens obtained between 6 and 39 gestational weeks were measured for 115 singleton insulin-dependent diabetic pregnancies without major fetal malformations or stillbirths. The fetuses of diabetics whose mean Hb A1c during pregnancy was 8.5% or more remained PG-negative more often than those in the pregnancies with the mean Hb A1c below 8.5% at 37 (4/7 vs. 8/68, chi 2 = 10.2, p less than 0.01) and 38 (2/7 vs. 2/84, chi 2 = 5.2, p less than 0.05) completed weeks of gestation. The fetuses of the patients with a mean Hb A1c 8.0% or more were more often PG-negative at 37 gestational weeks (7/15) than those in the pregnancies with a mean Hb A1c below 8.0% (5/60, chi 2 = 10.4, p less than 0.005). Because Hb A1c reflects long-term blood glucose levels, the results suggest that maternal hyperglycemia, or other metabolic disturbances associated with hyperglycemia, is the cause of delayed fetal lung maturation among insulin-dependent diabetics.