1. Department of Obstetrics The Juliane Marie Center for Children, Women, and ReproductionRigshospitaletUniversity of Copenhagen Copenhagen Denmark
2. Section of Biostatistics Department of Public Health University of Copenhagen Copenhagen Denmark
3. Department of Obstetrics and Gynecology Aarhus University Hospital Aarhus Denmark
4. Center for Environmental Research and Children's Health (CERCH) School of Public Health University of California Berkeley CA USA