1 Department of Obstetrics, Gynecology and Reproductive Sciences, Robert Larner College of Medicine, University of Vermont, Burlington, VT. Electronic address: [email protected].
2 Department of Obstetrics, Gynecology and Reproductive Sciences, Robert Larner College of Medicine, University of Vermont, Burlington, VT.
3 Department of Medical Biostatistics, Robert Larner College of Medicine, University of Vermont, Burlington, VT.