[1
]
Department of Obstetrics and Gynecology, Baystate Medical Center, Springfield, Massachusetts.
Electronic address: Cynthia.sites@baystatehealth.org.
[2
]
Department of Epidemiology and Biostatistics, Baystate Medical Center, Springfield,
Massachusetts.
[3
]
Department of Obstetrics and Gynecology, Baystate Medical Center, Springfield, Massachusetts.
[4
]
Massachusetts Department of Public Health, Boston, Massachusetts.
[5
]
Department of Obstetrics and Gynecology, University of Vermont, Burlington, Vermont.
[6
]
Centers for Disease Control and Prevention, Atlanta, Georgia.