Indicated preterm birth for placenta accreta.

The purpose of this article is to review the risks and benefits of scheduled preterm delivery in patients with placenta accreta, increta, and percreta and to provide guidance regarding timing of delivery in such cases. Relevant documents for this opinion were identified through a search of the English literature for publications, including one or more of the keywords "accreta" or "increta" or "percreta" and "preterm" and "delivery time" by the use of PubMed (U.S. National Library Of Medicine, January 1990-January 2010), with results limited to studies involving humans. Additional information was obtained from references identified from within selected articles, from additional review articles, and from guidelines by organizations, including the American College of Obstetricians & Gynecologists. Each included article was evaluated according to study design and quality in accordance with scheme outlined by the U.S. Preventative Services Task Force, and final recommendations are provided based on the level of published evidence. On the basis of this search, we found that abnormal placentation, encompassing placenta accreta, increta, and percreta, is increasingly common. We also found that randomized controlled trials and well-controlled observational studies that can be used to define best practice in delivery time are lacking. Optimal delivery time must be determined from available case series, retrospective reviews and decision analysis studies. Given the best-available evidence, optimal time for delivery is believed to be between 34 and 35 weeks in most cases.