Aim: The goal of this study is to investigate the association between higher parity and the risk of occurrence of type 2 diabetes mellitus (T2DM) in women and to quantify the potential dose-response relation.
Methods: We searched MEDLINE, and EMBASE electronic databases for related cohort studies up to March 10th, 2016. Summary rate ratios (RRs) and 95% confidence intervals (CIs) for T2DM with at least 3 categories of exposure were eligible. A random-effects dose-response analysis procedure was used to study the relations between them.
Results: After screening a total of 13,647 published studies, only 7 cohort studies (9,394 incident cases and 286,840 female participants) were found to be eligible for this meta-analysis. In the category analysis, the pooled RR for the highest number of parity vs. the lowest one was 1.42 (95% CI: 1.17-1.72, I2=71.5%, Pheterogeneity=0.002, Power=0.99). In the dose-response analysis, a noticeable linear dose-risk relation was found between parity and T2DM (Pfor nonlinearity test=0.942). For every live birth increase in parity, the combined RR was 1.06 (95% CI: 1.02-1.09, I2=84.3%, Pheterogeneity=0.003, Power=0.99). Subgroup and sensitivity analyses yielded similar results. No publication bias was found in the results.
Conclusion: This meta-analysis suggests that higher parity and the risk of T2DM show a linear relationship in women.
Keywords: Cohort studies; Dose–response; Meta-analysis; Parity; Type 2 diabetes mellitus.
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