1. Department of Healthcare Research; KHLim; Limburg Catholic University College; PHL University College; Hasselt; Belgium
2. Department of Healthcare Research; PHL University College; Hasselt; Belgium
3. Flemish Study Centre for Perinatal Epidemiology; Brussels; Belgium
4. Department of Obstetrics & Gynaecology; Division of Mother & Child; University Hospitals; Leuven; Belgium