en Systematic review and meta-analysis of mean age at menarche in Iranian girls Obstetrics and Gynecology Obstetrics and Gynecology پژوهشي Original Research <p><b>Background:</b> Many observational studies were published concerning the mean age at menarche and suggested those which may be a decreasing age at menarche in Iranian girls. The aim of this systematic review and meta-analysis was to estimate the overall mean age at menarche in Iranian girls.&nbsp;</p> <div><b>Methods:</b> We searched using online databases through December 2014 using and examined the reference lists of pertinent paper. Finally, 28 cross-sectional studies were selected for this meta-analysis. Cochran and tau-two tests were used for the detection of homogeneity of samples. The common average was calculated by random effect using RevMan 5 and Stata software. The cumulative meta-analysis and meta-regression were used to review the factors affecting heterogeneity.&nbsp; <div><b>Results:</b> The mean age at menarche was13.9 years before 2000 and after 2000 was 12.6 years. The overall mean (95% CI) age at menarche was calculated 12.872 (95% CI: 12.874, 12.870) years based on stochastic models.&nbsp;</div> <div><b>Conclusion:</b> These findings indicated that the mean age at menarche in Iranian girls was less than that of the region and developing countries therefore performing a systematic review and meta-analysis to evaluate related factors that influence age at menarche in Iranian girls could be beneficial.</div> </div> Age at menarche, Menstruation, Meta-analysis, Systematic review 27 33 http://caspjrm.ir/browse.php?a_code=A-12-1-11&slc_lang=en&sid=1 Farideh Mohsenzadeh- ledari 10031947532846001260 10031947532846001260 Yes Shahroud University of Medical Sciences, Shahroud, Iran Afsaneh Keramat 10031947532846001261 10031947532846001261 No Department of Reproductive Healths, School of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran Ahmad Khosravi 10031947532846001262 10031947532846001262 No Center for Health Related Social and Behavioral Sciences Research, Shahroud University of Medical Sciences, Shahroud, Iran