1. Department of Obstetrics and Gynecology, University of Massachusetts Medical School-Baystate, Springfield, Massachusetts, USA.
2. Department of Medicine, University of Massachusetts Medical School-Baystate, Springfield, Massachusetts, USA.
3. Department of Biostatistics and Epidemiology, School of Public Health & Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA.
4. Department of Maternal-Fetal Medicine, Boston Medical Center, Boston, Massachusetts, USA.
5. Department of Obstetrics and Gynecology, Boston Medical Center, Boston, Massachusetts, USA.