1. Department of Obstetrics and Gynecology, University of California, Los Angeles, Los Angeles, CA, USA;
2. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, Los Angeles, CA, USA;
3. David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA;
4. Department of Urology, University of California, Los Angeles, Los Angeles, CA, USA