Caesarean section and subsequent ectopic pregnancy: a systematic review and meta-analysis.

BACKGROUND: Caesarean section rates are increasing worldwide, and the long-term effects are unknown. OBJECTIVE: To evaluate the risk of subsequent ectopic pregnancy in women with a previous caesarean section, compared with vaginal delivery. SEARCH STRATEGY: Systematic review of the literature using CINAHL, the Cochrane Library, Embase, Medline, PubMed, SCOPUS and Web of Knowledge, published from 1945 until 17 July 2011. SELECTION CRITERIA: Cohort and case-control designs reporting on the mode of delivery and subsequent ectopic pregnancy. Two reviewers independently assessed the titles, abstracts, and full articles to identify eligible studies, using a standardised data collection form, and also assessed the study quality. Reference lists of the studies included were also cross-checked. DATA COLLECTION AND ANALYSIS: Odds ratios (ORs) were combined using a random-effect model to estimate the overall association between caesarean section delivery and the risk of subsequent ectopic pregnancy. MAIN RESULTS: Thirteen studies were included, which recruited a total of 61,978 women. Five studies reported adjustment for confounding factors, and the pooled OR of subsequent ectopic pregnancy following a caesarean section was 1.05 (95% CI 0.51-2.15). The removal of one study that reported outlier results yielded a pooled OR of 0.82 (95% CI 0.42-1.61). The pooled crude OR for all 13 studies was 1.36 (95% CI 0.99-1.88). AUTHOR'S CONCLUSIONS: This review found no evidence of an association between prior caesarean section delivery and the occurrence of a subsequent ectopic pregnancy, but the studies included were of poor or variable quality, and only a small number adjusted for potential confounding factors. Further research of a higher methodological quality is required to assess any potential association between mode of delivery and subsequent ectopic pregnancy.