The effect of polyhydramnios and oligohydramnios on fetal lung maturity indexes

The influence of amniotic fluid (AF) volume on common fetal lung maturity (FLM) indices was evaluated. Cases diagnosed with altered AF volume as estimated by ultrasound (n = 71; polyhydramnios = 33, oligohydramnios = 38) were matched to controls by: gestational age (GA) at amniocentesis, GA at delivery, neonatal weight, sex, and pregnancy complication. FLM was assessed on AF specimens obtained by transabdominal amniocentesis by planimetric and stechiometric L/S, phosphatidylglycerol (PG), and lamellar bodies counts (LB). In cases with polyhydramnios, L/S ratios (planimetric and stechiometric) were statistically lower in cases with respect to controls (2.1 +/- 0.9 vs. 2.8 +/- 1.0, p = 0.007, and 4.8 +/- 2.4 vs. 5.9 +/- 2.7, p < 0.04; respectively). Absence of PG was more frequent in (70.8% vs. 50%, p = 0.02). LB counts were lower in cases than in controls (15.5 +/- 12.1 x 10(3)/microL vs. 21.9 +/- 14.3 x 10(3)/microL, p < 0.05). In cases with oligohydramnios, no difference was found for planimetric and stechiometric L/S in comparison to controls (2.6 +/- 1.2 vs. 2.6 +/- 1.0, N.S. and 4.9 +/- 2.1 vs. 4.6 +/- 1.8, N.S.; respectively), absence of PG (62.5% vs. 50%, N.S.), and LB counts (27.2 x 10(3)/microL +/- 12.8 x 10(3)/microL vs. 28.6 x 10(3)/microL +/- 24.1 x 10(3)/microL, N.S.). In conclusion, oligohydramnios was not associated with altered FLM indices; in cases with polyhydramnios all FLM indices were significantly lower.