1 Department of Obstetrics and Gynecology, Columbia University Irving Medical Center, New York, NY.
2 Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, CA.
3 Department of Obstetrics and Gynecology, Columbia University Irving Medical Center, 622 W 168 St., New York, NY 10032.
4 Department of Obstetrics and Gynecology, Columbia University Irving Medical Center, 622 W 168 St., New York, NY 10032. Electronic address: amf2104@cumc.columbia.edu.