1. Department of Obstetrics; University Medical Center Utrecht; Utrecht The Netherlands
2. Centre for Infectious Disease Research, Diagnostics and Screening; National Institute for Public Health and the Environment; Bilthoven The Netherlands
3. Netherlands Perinatal Registry; Utrecht The Netherlands
4. Faculty of Social and Behavioural Sciences; Utrecht University; Utrecht The Netherlands
5. Netherlands Institute for Health Services Research; Utrecht The Netherlands
6. Foundation for Prenatal Screening Region of Utrecht; Utrecht The Netherlands