Assessment of fetal lung maturity: Relationship of gestational age and pregnancy complications to phosphatidylglycerol levels

Phosphatidylglycerol (PG) was measured in the pellet fraction of 863 amniotic fluid samples, and charts were reviewed for maternal disease, duration of gestation at collection, and outcome of pregnancy. PG was present at 32 to 34 weeks' gestation in 24.1% of samples; at 35 to 36 weeks, in 52.3%; and at 37 to 38 weeks, in 85.4%. Pre-eclamptic toxemia/hypertension, diabetes, premature rupture of membranes, and preterm labor all had earlier appearance of PG than a comparison group. There was no delay in lung maturity in gestational diabetics or Rh isoimmunization. Infants of patients with overt diabetes with PG ≥0.5% did not develop respiratory distress syndrome. This value appeared in 30% of diabetic patients by 35 to 36 weeks and in 76.9% by 37 weeks' gestation.