1. Department of Obstetrics and Gynecology, Temple University Hospital, Philadelphia, PA, USA
2. Biostatistics Consulting Center, Department of Biostatistics, Temple University School of Medicine, Philadelphia, PA, USA
3. Department of Obstetrics and Gynecology, Baystate Medical Center, Springfield, MA, USA
4. Department of Obstetrics and Gynecology, Albert-Einstein Medical Center, Philadelphia, PA, USA