Oligohydramnios in the second trimester of pregnancy, fetal breathing and normal lung growth.

Two patients with severe oligohydramnios in the second trimester, one due to spontaneous membrane rupture at 18 weeks and the other, uteroplacental insufficiency from 22 weeks were prospectively followed. In both cases despite severe oligohydramnios fetal breathing movements persisted and although one infant delivered at 28 weeks developed respiratory distress syndrome and the second meconium aspiration syndrome neither had evidence of pulmonary hypoplasia. We conclude the presence of fetal breathing movements, despite oligohydramnios, may preserve lung growth, and may act as a predictor of favourable neonatal outcome.