Persistent pulmonary hypertension of the newborn in extremely preterm infants: a Japanese cohort study.

Objective: To investigate the characteristics of persistent pulmonary hypertension of the newborn (PPHN) in extremely preterm infants and its impact on neurodevelopmental outcomes at 3 years of age.

Methods: A retrospective multicentre cohort study. Methods: 202 tertiary perinatal centres registered in the Neonatal Research Network of Japan (NRNJ). Methods: Infants born at <28 weeks of gestational age (GA), between 2003 and 2012, were extracted from tertiary perinatal centres participating in NRNJ. Methods: Demographic characteristics, morbidity, interventions and mortality were compared for infants with and without PPHN. Multivariable logistic analysis was performed to evaluate the impact of PPHN on long-term neurodevelopmental outcomes (the prevalence rate of cerebral palsy, need for home oxygen therapy, and visual, hearing and cognitive impairment) at 3 years of age.

Results: The prevalence of PPHN among the 12 954 extremely preterm infants enrolled was 8.1% (95% CI 7.7% to 8.6%), with the trend increasing annually, and a higher proportion as GA decreased: 18.5% (range, 15.2% to 22.4%) for infants born at 22 weeks compared with 4.4% (range, 3.8% to 5.2%) for those born at 27 weeks. Clinical chorioamnionitis and premature rupture of membranes were associated with PPHN. On multivariate analysis of the data from 5923 infants followed up for 3 years, PPHN was a significant independent risk factor for visual impairment (adjusted OR, 1.42, 95% CI 1.03 to 1.97).

Conclusions: The prevalence of PPHN in extremely preterm infants has been increasing over the past decade in Japan. Clinicians should be aware of visual impairments as a neurodevelopmental abnormality among infants with PPHN.