Study population
The Generation R Study is a multi-ethnic, population-based, prospective
cohort from fetal life onwards. This cohort has previously been
described in detail.20, 21 Briefly, all pregnant women
residing in Rotterdam with a planned delivery date between April 2002
and January 2006 were invited to participate and 9,778 (response rate
61%) women enrolled. The variable of interest, gestational age at
antenatal care initiation, was available for 4,196 women. The Medical
Ethics Committee of Erasmus MC in Rotterdam, the Netherlands, has
approved the study in accordance with the Declaration of Helsinki of the
World Medical Association. Written informed consent was obtained from
all participants.