1. Center for Clinical Transfusion Research Sanquin Research Leiden the Netherlands
2. Department of Obstetrics Leiden University Medical Center Leiden the Netherlands
3. National Perinatal Epidemiology Unit (NPEU) University of Oxford Oxford UK
4. Faculty of Science Athena Institute VU University Amsterdam Amsterdam the Netherlands
5. Department of Clinical Epidemiology Leiden University Medical Center Leiden the Netherlands
6. Department of Biomedical Data Sciences Leiden University Medical Center Leiden the Netherlands
7. Department of Obstetrics Birth Center Wilhelmina Children Hospital Division Woman and Baby University Medical Center Utrecht Utrecht the Netherlands