1. Barnard College, Columbia University, New York, NY, USA
2. Department of Obstetrics and Gynecology, Columbia University, New York, NY, USA
3. Department of Health Policy and Management, Columbia Mailman School of Public Health, New York, New York, USA
4. Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California-San Francisco, San Francisco, CA, USA