1. Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, UT, USA;
2. Intermountain Healthcare Division of Maternal Fetal Medicine, Salt Lake City, UT, USA;
3. Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, NC, USA;
4. Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA