1. Department of Epidemiology Graduate School of Public Health University of Pittsburgh Pittsburgh PA USA
2. Department of Obstetrics, Gynecology, and Reproductive Sciences School of Medicine University of Pittsburgh Pittsburgh PA USA
3. Magee‐Womens Research Institute Pittsburgh PA USA
4. School of Public Health University of California at Berkeley Berkeley CA USA
5. Department of Obstetrics and Gynecology Indiana University School of Medicine IN USA
6. Department of Obstetrics and Gynecology University of Utah Salt Lake City UT USA
7. Department of Obstetrics and Gynecology University of Pennsylvania School of Medicine Philadelphia PA USA
8. Department of Obstetrics and Gynecology University of California Irvine College of Medicine Irvine CA USA