1. Department of Obstetrics; Leiden University Medical Center; Leiden the Netherlands
2. Department of Obstetrics and Gynecology; Medical Center Haaglanden; The Hague the Netherlands
3. Department of Cardiology; Leiden University Medical Center; Leiden the Netherlands
4. Department of Clinical Epidemiology and Department of Medical Statistics and Bioinformatics; Leiden University Medical Center; Leiden the Netherlands
5. Department of Obstetrics and Gynecology; VU University Medical Center; Amsterdam the Netherlands
6. Department of Clinical Chemistry; Leiden University Medical Center; Leiden the Netherlands
7. Department of Obstetrics Birth Center Wilhelmina's Children Hospital; Division Women and Baby; University Medical Center Utrecht; Utrecht the Netherlands