Age at Menarche in South Asia: An Interplay of Sociodemographic, Nutritional, Lifestyle, Anthropometric, Biological and Environmental Factors – A Systematic Review

eview question / Objective The present review aims to examine evidence on sociodemographic, nutritional, lifestyle, anthropometric, biological, and environmental factors associated with age at menarche among females aged 8-21 years in South Asia.Rationale An early or late age at menarche is associated with significant long-term health complications Evidence suggests that early age at menarche is associated with an increased risk of breast and endometrial cancers, obesity, and cardiometabolic disorders such as type 2 diabetes While delayed onset is associated to long-term health problems such as osteoporosis-sis, poor bone mineral density, subfertility, and psychosocial stress Subsequently, the trajectory of healthy aging can be affected by these factors.The cooccurrence of early age at menarche among overnourished females and delayed menarche in undernourished females exacerbates the dual burden of malnutrition.This pattern is distinct in South Asia, highlighting the nutritional transition and related challenges faced by this region.In addition to social, nutritional, and lifestyle transition, biological factors, specifically heredity, are also identified as a strong influencing factor that determines the age at menarche.The early life environment, particularly during the developmental phase, is influenced by certain factors, including maternal age, nutritional status, prenatal nutrition, and birth order, which significantly impact birth weight and fetal development, and eventually influence the age at menarche.Additionally, Exposure to poor environmental factors, including household use of smoking, alcohol, and tobacco; climate change; exposure to environmental toxins, a n d e n d o c r i n e -d i s t u r b i n g c h e m i c a l s a re recognized as a key driver of menarcheal timings.Despite growing evidence, a wide range of differences in the age at menarche without any specific pattern has been observed across South Asia.These disparities are attributed to the complex interplay of sociodemographic factors,