1. Department of Obstetrics and Gynecology , Johns Hopkins University School of Medicine , Baltimore , MD , USA
2. Center for Maternal Fetal Medicine , Howard County General Hospital , Columbia , MD , USA
3. Department of Obstetrics and Gynecology , St Francis Hospital and Medical Center , Hartford , CT , USA
4. Division of Obstetrics and Gynecology , University of New England College of Osteopathic Medicine , Biddeford , ME , USA
5. Frank Netter School of Medicine , Quinnipiac University , North Haven , CT , USA
6. Department of Obstetrics and Gynecology , Oakland University William Beaumont School of Medicine, Beaumont Medical Center , Detroit , MI , USA