Antenatal care initiation
Information about the timing of antenatal care initiation was derived
from electronic patient files (Micronatal®) of 10 midwifery practices in
Rotterdam.22 The gestational age was determined by
ultrasound. The gestational age at antenatal care initiation was used as
a continuous variable indicating the gestational age in weeks at the
first visit. In addition, to show the number of pregnancies that did not
meet the recommendations of the Dutch Society of Obstetrics and
Gynaecology (NVOG) for basic antenatal care at the time of data
collection, we created a dichotomous variable indicating whether
initiation was within or after 14 weeks gestational
age.23