High parity is associated with increased risk of cervical cancer: Systematic review and meta-analysis of case-control studies

Background: Cervical cancer is the fourth most common cancer among women. High parity has long been suspected with an increased risk of cervical cancer. Evidence from the existing epidemiological studies regarding the association between parity and cervical cancer is variable and inconsistent. Therefore, the objective of this systematic review and meta-analysis was to synthesize the best available evidence on the epidemiological association between parity and cervical cancer. Methods: MEDLINE/PubMed, HINARI, Google scholar, Science direct, and Cochrane Libraries were systematically searched. Cochrane Q statistics and I2 tests were performed to assess heterogeneity among included studies. Begg's test and egger's regression analysis were performed to assess publication bias. A random-effect meta-analysis model was used to compute pooled odds ratio of the association between parity and cervical cancer. Results: A total of 6975 participants (1998 patients; 4977 controls) were incorporated in the 13 articles included in the final meta-analysis. The meta-analysis revealed that women with parity greater than or equal to three had 2.4 times higher odds of developing cervical cancer compared to women with parity less than three [pooled odds ratio (POR) = 2.4, 95% CI: 1.9-3.2]. Conclusion: High parity is associated with an increased risk of cervical cancer. Strong epidemiological studies are recommended to further explore the mechanisms and role of parity in the causation of cervical cancer.