Timing of Menarche in Relation to Physical Growth Patterns among Girls in Sumbawa Island

Abstract

Menarche is a key marker of girls sexual maturity and is closely linked to physical growth during puberty, which is influenced by genetic, environmental, and biocultural factors. Although studies on menarche and growth have been conducted in several Indonesian populations, information on the timing of menarche and physical growth is limited for girls in Sumbawa Island, which has ecological and social characteristics that differ from those of the larger islands in Indonesia. Therefore, this study aimed to characterize the timing of menarche in relation to physical growth patterns and to determine the influence of sociodemographic factors on physical growth among girls in Sumbawa Island. A cross-sectional study was conducted among 374 girls aged 6–20 years from Sumbawa Island, Indonesia. Menarche status was assessed using the status quo method, and median age at menarche was estimated using a generalized linear model (GLM) with a probit link. Age-specific growth curves for height, weight, body mass index (BMI), and percentage body fat (PBF) were constructed using the generalized additive model for location, scale, and shape (GAMLSS). The relationship between household income and physical growth indicators was evaluated using a GLM after adjusting for chronological age. The estimated median age at menarche was 12.2 years. Peak height velocity occurred at 9.5 years of age, approximately 2.7 years before menarche, whereas peak weight velocity occurred at 11.2 years of age, approximately one year before menarche. Meanwhile, peak BMI velocity and peak body fat percentage (PBF) velocity occurred near the age of menarche, with both peaking at 12.5 years of age, approximately 0.3 years after menarche. At menarche, girls had reached a median height of 143.05 cm (92.9% of adult height), weight of 33.78 kg (69.7% of adult weight), BMI of 16.5 kg/m² (82.5% of adult BMI), and PBF of 21.32% (82.4% of adult PBF). Household income was positively associated with BMI but not significantly associated with height, weight, or PBF. These findings suggest that most linear growth occurs before menarche, while increases in body mass and adiposity continue after the onset of reproductive maturation. The observed relationship between menarche timing and physical growth patterns is consistent with the developmental framework of life history theory. The relatively early menarche observed in this population may be interpreted within the context of Sumbawa Island's semi-urban characteristics, whereas variation in physical growth patterns may be associated with environmental conditions and sociodemographic factors.