A systematic review and meta-analysis of cesarean delivery and other uterine surgery as risk factors for placenta accreta.

Background: The incidence of placenta accreta has increased in recent years and it has been suggested that the rising trend in cesarean delivery and other uterine surgery is the underlying cause.

Objective: To explore the magnitude of the effect of performing single and repeat cesarean deliveries or other uterine surgery on the incidence of placenta accreta.

Search Strategy: Relevant databases were searched for papers published before August 1, 2018, using terms including "accreta" and "cesarean."

Selection Criteria: Cohort studies assessing the risk of placenta accreta according to women's history of uterine surgery.

Data Collection And Analysis: Meta-analyses were performed to assess the risks associated between uterine surgery and placenta accreta, hysterectomy, and uterine rupture. The I statistic was used to examine between-study heterogeneity.

Main Results: The risk of placenta accreta in a second pregnancy increased for women who had undergone a cesarean in their first pregnancy compared with vaginal delivery (OR 3.02; 95% CI, 1.50-6.08). Absolute risk of placenta accreta increased with the number of previous cesareans. The risk of uterine rupture and hysterectomy was also associated with the number of cesareans.

Conclusions: Risk of placenta accreta, hysterectomy, and uterine rupture increases with the number of previous cesarean deliveries.

Prospero: CRD42016050646.