Early Menarche and Risk of Metabolic Syndrome: A Systematic Review and Meta-Analysis

Background: The association between age at menarche and metabolic syndrome was inconsistent across studies and remains unclear. We conducted a systematic review and meta-analysis of observational studies to assess the association between age at menarche and risk of metabolic syndrome, comprehensively. Materials and Methods: The PubMed and ISI Web of Science databases were searched for all articles published through May 2017, and the reference lists of the retrieved articles were reviewed. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model through combining the study-specific estimates adjusting for potential confounders. Results: Sixteen observational studies were eligible for the meta-analysis of age at menarche and metabolic syndrome, which included 13,657 cases among 51,453 subjects. The pooled RR of metabolic syndrome for the youngest versus the oldest categories of age at menarche was 1.62 (95% CI: 1.40-1.88) (p for heterogeneity=0.01, I-2=57.3%). The analysis of 1-year decrease in age at menarche conferred a pooled RR of 1.08 (95% CI: 1.01-1.15), suggesting an 8% increase in risk of metabolic syndrome. The association between age at menarche and the risk of metabolic syndrome did not vary by study design, geographical region, number of subjects, and adjustment for confounders. Conclusions: Our findings from the current meta-analysis suggest that earlier menarcheal age is associated with higher risk of metabolic syndrome. Age at menarche may help identify women with higher risk of metabolic syndrome. Further well-designed cohort studies are warranted to provide definitive evidence.