Surfactant associated protein (SAP-35) in amniotic fluid from diabetic and nondiabetic pregnancies.

We have recently shown that, with the current management of insulin-dependent diabetes during pregnancy, infants of diabetic mothers are at no greater risk of respiratory distress syndrome (RDS) than an appropriately matched control population. A previous study suggested a selective inhibition of surfactant associated protein of 35,000 daltons (SAP-35) in the amniotic fluid of diabetic pregnancies. In order to determine whether a selective inhibition of SAP-35 occurs in well controlled, insulin-dependent diabetic pregnancies, we compared SAP-35 concentration and lecithin/sphingomyelin (L/S) ratios in amniotic fluid from 30 well controlled, insulin-dependent women with 30 nondiabetic pregnant women pair-matched for gestational age, race, and indication for amniocentesis. Gestational ages ranged from 30-43 weeks, with a mean of 36.5 +/- 2.5 weeks, in both groups. Surfactant associated protein-35 was measured by an enzyme-linked capture immunoassay specific for SAP-35 and its oligomers. Mean +/- SEM SAP-35 was 3.7 +/- 0.4 micrograms/mL (N = 30) in the diabetic group, not significantly different from 5.0 +/- 1.1 micrograms/mL (N = 30) in the control group (P greater than .05). Mean L/S ratios were also not different: 2.4 +/- 0.1 (diabetic) compared with 2.3 +/- 0.1 (control); P greater than .05. The rate of RDS was similar in both groups. We conclude that in well controlled diabetic pregnancies, fetal lung maturation, as assessed by the L/S ratio, SAP-35 concentration, and outcome, is not adversely affected.