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: Case-control studies reporting the association between parity and cervical cancer were systematically searched in databases like MEDLINE/PubMed, HINARI, Google scholar, Science direct, and Cochrane Libraries. All studies fulfilling the inclusion criteria and published between 2000 and 7 March 2020 were included in this meta-analysis. This study reported according to PRISMA guideline. Cochran's Q-statistics and I-2 tests were performed to assess heterogeneity among included studies. Egger's regression analysis was 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 6685 participants (3227 patients and 3458 controls) were incorporated in the 12 studies included in this meta-analysis. The meta-analysis revealed that women with high parity had 2.65 times higher odds of developing cervical cancer compared to their counterparts (odds ratio = 2.65, 95% confidence interval = 2.08-3.38). Conclusion: High parity is positively associated with cervical cancer. Strong epidemiological studies are recommended to further explore the mechanisms and role of parity in the causation of cervical cancer.