Factors Related to the Age at Menarche in Iran: A Systematic Review and Meta-Analysis

Background Reduced age at menarche is an important health indicator for women and may be associated with complications such as an increased risk of asthma, breast cancer, ovarian cancer, type 2 diabetes. We aimed to examine the factors related to the age at menarche in Iran. Materials and Methods: In this systematic review and meta-analysis, an advanced search with no time restriction was conducted in online databases such as the Web of Science, Embase, Medline, Scopus, and Persian databases of SID and Magiran, as well as the Google Scholar search engine, until the end of 2019. The publication heterogeneity and bias of the extracted studies were evaluated by the Q test and Begg's test, respectively. Results: In this study, 12 articles with a total sample size of 17672 were included. Based on the findings of these studies, the body mass index (BMI), the mother's age at menarche, physical activity, nutrition, and socioeconomic status were correlated with the age at menarche for Iranian girls. A negative correlation was found between BMI (r=-0.07), and socioeconomic status (r=-0.57) with the age at menarche (P<0.05). A positive correlation existed between the girl's age at menarche and that of the mother (r=0.42, P<0.05). Moreover, correlation was weak and positive between the age at menarche and physical activity (r=0.14, P<0.05). The quantitative results of the studies were incomplete to establish a relationship between nutrition and age at menarche. Conclusion Due to the effects of numerous factors on the age at menarche, it is suggested that longitudinal studies be conducted to investigate the role of all the known factors, especially environmental factors, on the age at menarche.