1. Department of Obstetrics and Gynecology; Eastern Virginia Medical School; Norfolk VA USA
2. Graduate Program in Public Health; Eastern Virginia Medical School; Norfolk VA USA
3. Department of Obstetrics and Gynecology; College of Physicians and Surgeons; Columbia University; New York NY USA
4. Department of Obstetrics and Gynecology; Winthrop University Hospital; Mineola NY USA
5. Department of Epidemiology; Joseph L. Mailman School of Public Health; Columbia University; New York NY USA