Longitudinal assessment of infant lung function following pregnancies complicated by prolonged and preterm rupture of the membranes.

Serial measurements of functional residual capacity (FRC) were made in 22 infants (median gestational age at delivery 32 weeks, range 25-40) during the first 2 years of life. All infants had been delivered from pregnancies complicated by prolonged and preterm rupture of the membranes (PPROM) of at least 1 week in duration. The onset of membrane rupture was at a median of 26 weeks (range 15-32) with a median duration of 5.5 weeks (range 1-21). The mean FRC at all postnatal ages studied: 25 ml/kg at 6 and 12 months and 24 ml/kg at 18 and 24 months did not differ significantly from the control population (mean 24 ml/kg). There was, however, a wider scatter of results in the study population: four infants born very preterm consistently had FRC results above the 95% confidence limits of the controls but only two infants had FRCs consistently below this range. These results suggest PPROM may not be an invariable association of abnormal antenatal lung growth.