[1] University of California—San Francisco,Department of Obstetrics, Gynecology & Reproductive Sciences
[2] University of California—San Francisco,Department of Family and Community Medicine
[3] University of California—San Francisco,Department of Epidemiology and Biostatistics
[4] University of California—San Francisco,School of Medicine
[5] University of South Florida Morsani College of Medicine,Department of Obstetrics and Gynecology
[6] The Warren Alpert Medical School of Brown University,Department of Obstetrics and Gynecology