Risk factors for persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn, a clinical syndrome that results from the failure of the normal fetal-to-neonatal circulatory transition, is associated with substantial infant mortality and morbidity. We performed a case-control study to determine possible antenatal and perinatal predictors of persistent pulmonary hypertension of the newborn.

Between 1998 and 2003, the Slone Epidemiology Center enrolled 377 mothers of infants with persistent pulmonary hypertension of the newborn and 836 mothers of matched control subjects. Within 6 months of delivery, study nurses interviewed participants regarding demographic, medical, and obstetric characteristics.

Factors that were independently associated with an elevated risk for persistent pulmonary hypertension of the newborn were infant male gender and black or Asian maternal race compared with white race. High prepregnancy BMI (>27 vs <20) was also associated with persistent pulmonary hypertension of the newborn, as were diabetes and asthma. Compared with infants who were delivered vaginally, the risk for persistent pulmonary hypertension of the newborn was higher for those who were born by cesarean section. Compared with infants who were born within 37 to 41 gestational weeks, the risk was higher for those who were born between 34 and 37 completed weeks and for those born beyond 41 weeks. Compared with infants within the 10th and 90th percentiles of birth weight for gestational age distribution, the risk was higher for infants above the 90th percentile.

Our findings suggest an increased risk for persistent pulmonary hypertension of the newborn associated with cesarean delivery; late preterm or postterm birth; being large for gestational age; and maternal black or Asian race, overweight, diabetes, and asthma. It remains unclear whether some of these factors are direct causes of persistent pulmonary hypertension of the newborn or simply share common causes with it; however, clinicians should be alert to the increased need for monitoring and intervention among pregnancies with these risk factors.