Systemic hypertension in very preterm infants: a population-based study

The purpose of this study is to assess incidence, temporal trend, risk factors, clinical characteristics, management and outcomes of systemic hypertension (SH) in very preterm infants. We conducted a retrospective population-based study including preterm infants born at < 31 weeks' gestation in Nova Scotia and Prince Edward Island, Canada, between 2002 and 2016. Patients diagnosed with SH requiring treatment before discharge from the NICU, or on 3 consecutive occasions during outpatient follow-up, were compared with matched controls (for gestational age, sex and birth weight). Perinatal data, details of SH, neonatal course and neurodevelopmental outcomes at 18 months corrected gestational age were reviewed. Of the 935 infants who met inclusion criteria, 102 (10.9%) had SH. Mean (SD) gestational age at birth was 27.1 (1.9) weeks. Median (IQR) corrected gestational age at diagnosis was 40 (37, 57) weeks. There was a significant reduction in the incidence of SH over the 15-year study period from 12.8 to 7.2% (p = 0.02). On logistic regression analysis, only intrapartum magnesium sulfate was associated with decreased odds of SH (aOR 0.25, 95% CI 0.08, 0.73). There were no significant differences in mortality, length of hospital stays, mean mental development index, cognitive, language, and motor scores between SH patients and their matched controls.

The incidence of SH in very preterm infants was 10.9% with a declining trend over the study period. Administration of antenatal magnesium sulfate was associated with reduced odds of SH. Systemic hypertension does not appear to be negatively associated with neonatal mortality, length of hospital stay, or neurodevelopmental outcomes at 18 months corrected age.

• Systemic hypertension in very preterm infants is not uncommon. • This significant health condition warrants more attention and research to guide clinical practice.

• The incidence of systemic hypertension in our study was 10.9% with a declining trend. • Approximately one third of infants were diagnosed after NICU discharge. • Approximately two thirds of the hypertensive infants had nephrocalcinosis. • Systemic hypertension was not associated with increased mortality, short-term morbidities, or neurodevelopmental impairment at 18 months corrected age.