Sex differences in expiratory airflow among survivors born before 28 weeks’ gestation or under 1000 g birthweight, and normal birthweight controls

Expiratory airflow was measured by spirometry at ages 8 years, 18 years and 25 years in 297 survivors born extremely preterm (EP; <28 weeks' gestation) or extremely low birth weight (ELBW; <1000 g) and 260 normal birth weight (>2499 g) controls. At 8 years, expiratory airflows were similar between males and females in both EP/ELBW and control groups. Worsening expiratory airflows with increasing age were noted in the EP/ELBW group but not controls. Specifically, males born EP/ELBW had z-scores for forced expired volume in 1 s which were lower by a mean of -0.17 SD per decade (95% CI -0.27 to -0.07), p=0.001.