Fetal breathing movements in pregnancies complicated by premature membrane rupture in the second trimester.

Forty pregnancies complicated by oligohydramnios in the second trimester due to prolonged and premature membrane rupture (PPROM) were followed prospectively to determine factors influencing fetal breathing activity and the relationship of fetal breathing movements (FBM) to outcome. The patients were retrospectively divided into three groups according to the presence or absence of FBM. Membrane rupture occurred at a significantly earlier gestation in those pregnancies in which FBM were absent. Duration of membrane rupture only differed significantly between pregnancies in which FBM were intermittent or consistently present. In the group in which FBM were always absent (N = 12) all the infants died in utero or in the neonatal period due to pulmonary hypoplasia. In the group with FBM always present (N = 17) all infants survived. In the third group FBM were observed in some, but not all, ultrasound examinations (N = 11). Some infants survived (N = 6), while others died either due to pulmonary hypoplasia or neonatal sepsis. These results show the necessity for several serial ultrasound examinations, all demonstrating the absence of fetal breathing movements, before pulmonary hypoplasia in PPROM can be predicted confidently.