Glycosylated Hemoglobin as a Predictor of Fetal Pulmonic Maturity in Insulin-Dependent Diabetes at Term

Abstract

In insulin dependent diabetic (IDDM) gestations, fetal pulmonary maturity is delayed in the presence of suboptimal glycemic control. Serum glycosylated hemoglobin (HbA_1c) provides a means of assessing glycemic control. We evaluated maternal HbA_1c in IDDM pregnancies at term undergoing amniocentesis for lung maturity to establish if euglycemia is associated with improved fetal lung maturity. Between July 1995 and June 1996, IDDM patients undergoing amniocentesis at term for lung maturity studies had a maternal serum sample analyzed for HbA_1c. Fetal lung maturity was established by the presence of phosphatidylglycerol (PG) in amniotic fluid. HbA_1c was considered elevated if >6.2%. Mean HbA_1c level was 6.8% (range 4.4 to 9.9%). PG was present in 54% of patients with elevated HbA_1c (7/13) versus 80% of those with normal HbA_1c (8/10) (p = 0.4). Although birth weight was higher in the elevated than in the normal HbA_1c group (3770 ±514 vs. 3215 ± 610 g), no association was present between birth weight and HbA_1c level (r = 0.22, p = 0.4). The rate of a mature pulmonic profile at term is not significantly different between IDDM women with good or poor glycemic control. HbA_1c values should not be used to predict the presence or absence of amniotic fluid PG.