Neonatal-perinatal risk factors for the development of persistent pulmonary hypertension of the newborn in preterm newborns

There is a long-held belief that preterm newborns lack sufficient arteriola r musculature to maintain a prolonged elevated pulmonary vascular resistanc e (PVR) after birth. Net ductal flow is thought to be minimal, with the dev eloping pulmonary circulation incapable of significant vasoconstriction. We identified retrospectively 15 premature newborns over a 10-year period wei ghing less than or equal to 1500 g and with a gestational age of less than or equal to 30 weeks with documented persistent pulmonary hypertension of t he newborn (PPHN) in the first 24 hours after birth. We matched 36 newborns of similar weight and gestation with no clinical evidence of shunting. The control group weaned to an FiO(2) less than or equal to 0.50 by 12 hours a fter birth. Despite similar gestational ages, the PPHN group (n = 15) had s ignificantly higher birth weights than the control group (n = 36). The dura tion of ruptured membranes, maternal tobacco use, and use of antenatal ster oids were significantly higher in the PPHN group. We speculate that these t hree factors might act in a synergistic relationship with which to accelera te pulmonary vascular smooth muscle development in premature newborns.