The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine nominated the systematic review to AHRQ and participated in protocol development and review of the draft of the report that formed the basis for this manuscript. The funder and nominators participated in protocol development and provided feedback for the Comparative Effectiveness Review report. They did not participate in selection of studies, extraction of data, evalu-ation of studies, interpretation of data, writing of the report or manuscript, or decision to submit the manuscript.The authors thank Jill Huppert, MD, MPH, our AHRQ Task Order Officer, and Anjali Jain, MD, AHRQ Medical Officer, for their guidance through the systematic review process; members of the Key Informant and Technical Expert Panels, reviewers of our overall review (all listed in the AHRQ full report); and, in particular, Monika Reddy Bhuma, BDS, MPH, dedicated research associate, who played a major role in conducting the overall review.Each author has confirmed compliance with the journal's requirements for authorship.