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.