Data sources
Data for this study were extracted from a national cohort using the Netherlands Perinatal Registry (www.Perined.nl). The Perined registration consists of population-based clinical and laboratory data on pregnancies, deliveries and neonatal (re)admissions until 28 days after delivery. Data in this national registry are collected by caregivers. The database covers about 96% of all deliveries at more than 22 completed weeks of gestation in the Netherlands.(16)
For this study we selected all singletons liveborn between 35+0 and 42+6 weeks of gestation in the period between January 1st 2010 and December 31st 2019. We did not include more recent years 2020 and 2021 because of the possible influence of the COVID-19 pandemic.(17) Infants with severe congenital malformations and infants who died before or during birth (defined as fetal mortality) were excluded.