The Contribution of Hypertensive Disorders of Pregnancy to Neonatal Unit Admissions and Iatrogenic Preterm Delivery at < 34+0 Weeks' Gestation in the UK: A Population-Based Study Using the National Neonatal Research Database.

Abstract

The objectives of this study were to (i) quantify the contribution of maternal hypertensive disorders of pregnancy (HDP) to iatrogenic preterm birth (PTB) and neonatal unit (NNU) admissions < 34+0 weeks and (ii) describe short-term population-level outcomes for HDP infants, exploring ethnic disparities and comparing outcomes by HDP exposure. Retrospective population-based study using the National Neonatal Research Database. England and Wales. Infants born < 34+0 weeks and admitted to NNU 2012-2020. Descriptive statistics, linear and logistic regression models to compare outcomes between groups. Survival to discharge with/without comorbidity. 122 228 infants met inclusion criteria. Where collected, 49 839/114 164 (43.7%, 95% CI 43.4%-43.9%) of infants had an iatrogenic PTB. HDP was recorded in 16 510/122 228 (13.5%) of all infants and 13 560/49 839 (27.2%) of iatrogenic PTBs. HDP and/or foetal growth restriction (FGR) were recorded in 24 124/49 839 (48.4%) of iatrogenic PTBs. Singleton HDP infants < 10th BWC had ≥ 90% survival to discharge from 28 weeks' gestation, versus from 26 weeks' gestation for those born ≥ 10th BWC. In extreme preterm HDP infants (< 27 weeks), 27.3% of infants < 10th BWC died compared to 15.2% of those ≥ 10th BWC. Survival without comorbidity was ≥ 90% from 32 weeks' gestation in HDP infants across BWC. These contemporaneous population-level data show that almost one in two PTB < 34+0 weeks' gestation are iatrogenic, with HDP and/or FGR being the major contributors to iatrogenic prematurity. This has substantial implications for strategies to reduce preterm birth in the UK and internationally. The data further inform antenatal and at-birth counselling of HDP-exposed infants.