Effects of fetal growth restriction on lung development before and after birth: A morphometric analysis

Our aim was to determine the effects of fetal growth restriction (FGR) duri ng late gestation on the structure of the lungs in the fetus near term and at 8 weeks after birth. The studies were performed using two groups of preg nant sheep and their offspring. In both groups, FGR was induced by umbilico -placental embolisation (UPE); for fetal studies, UPE was performed from 12 0 days of gestation until 140 days (term, similar to 146 days), when fetuse s were killed for tissue analysis. For postnatal studies, UPE continued fro m 120 days until delivery at term; postnatal lambs were killed at 8 weeks a fter birth for tissue analysis. UPE led to a thicker pulmonary blood-air barrier at 140 days of gestation a nd this difference, which was due to a thickened basement membrane, was sti ll present at 8 weeks after birth. At 8 weeks, we also observed a smaller n umber of alveoli per respiratory unit, thicker interalveolar septa, and a g reater volume density of lung tissue in FGR lambs compared to controls. The se changes would be expected to impair gas exchange and alter the mechanica l properties of the lungs. Our data. show that structural alterations in the lungs induced by placenta l insufficiency were more evident at 8 weeks of postnatal age than near ter m, indicating that the effects of FGR on the lung may become more serious w ith age and may affect respiratory health later in life. (C) 2001 Wiley-Lis s, Inc.