Timing of Pubertal Milestones in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Abstract

Despite increasing global attention to adolescent health in low- and middle-income countries (LMICs), limited literature exists on the timing of pubertal development in these settings. This study aimed to determine the age at menarche (AAM) and age of puberty onset [female Tanner Stage Breast 2 (B2) and male Tanner Stage Genital 2 (G2)] among healthy adolescents living in LMICs. It also aimed to explore the impact of nutritional status on pubertal timing in this population. MEDLINE, Embase, Cochrane CENTRAL, Web of Science, Scopus, and grey literature databases were searched. Observational studies and control arms of randomized controlled trials (RCTs) with healthy participants from LMICs born in or after 1998 were included. Pooled estimates with 95% CIs were calculated by random-effects meta-analyses using the DerSimonian and Laird inverse variance method for each pubertal milestone and by BMI category subgroups. Twenty-seven studies were included in the meta-analysis, representing 90,188 adolescents (78.3% female). Pooled mean estimates for AAM for normal, thin, and overweight BMI groupings were 12.3 y (95% CI: 12.1, 12.5), 12.4 y (95% CI: 12.2, 12.6), and 12.1 y (95% CI: 11.7, 12.5), respectively. For Tanner Stage B2, pooled mean age estimates for normal, thin, and overweight BMI groupings were 10.4 y (95% CI: 9.2, 11.6), 10.2 y (95% CI: 9.3, 11.4), and 8.4 y (95% CI: 6.8, 10.0), respectively. Finally, for Tanner Stage G2, pooled mean estimates for normal, thin, and overweight BMI groupings were 11.0 y (95% CI: 10.3, 11.7), 11.3 y (95% CI: 9.8, 12.9), and 10.3 y (95% CI: 10.0, 10.6), respectively. Data on the timing of pubertal milestones has traditionally come from high-income settings. In this systematic review of contemporary data from adolescents in LMICs, AAM, as well as age at pubertal onset, were similar to those reported from high-income settings.

Can the Neuromuscular Performance of Young Athletes Be Influenced by Hormone Levels and Different Stages of Puberty?

“…At the biological level, we can highlight the puberty process, which is the triggering of improvements in neurological, muscular, skeletal, and endocrine systems [6]. Among the environmental factors, we can highlight the level of physical activity, nutrition and quality of sleep, which are extremely important for the quality of the biological maturation process [7,8].…”

“…Sex hormones, such as estradiol, testosterone, and growth hormone, have extremely important functions in human biological development, which can mainly affect morphological structure, skeletal growth, and muscle strength levels [9][10][11][12][13][14][15][16][17]. In this context, among neuromuscular parameters, muscle strength and body speed are two of the most essential for body functionality in relation to physical health, and for the development of specific skills related to sports performance [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Characterization of pubertal development of girls in rural Bangladesh

“…We have also placed our findings in context of relevant studies in the literature since the late 1970s, prioritized by their multiple pubertal milestones estimated with the use of probit analysis ( Table 4 ). Also relevant, are findings from a recent meta-analysis of 27 studies in adolescent populations born in or after 1998 in low and middle income countries (LMICs) that reported pooled mean ages of 10.4 and 12.3 years for breast development and menarche, respectively [ 2 ]. From these comparisons, rural Bangladeshi girls appear to be maturing later than other adolescent populations in LMICs.…”

“…Of note, 19 out of 27 studies included in the meta-analysis came from urban settings, which could affect developmental timing. Also, a later menarche was observed in studies from African than Asian countries, at ages 13.8 versus 12.3 years, respectively [ 2 ]. Together, these studies reveal variation in pubertal timing by country over a period of five decades within LMICs and that pubertal timing in our study population plausibly reflects later pubertal development in rural contexts.…”

“…South Asia is a region undergoing rapid changes including growing wealth, shifting diets and decreasing physical activity [ 1 ]. These changes may influence the timing of sexual maturation of populations in the region [ 2 ], as indicated by an estimate of the onset of the primary sex characteristic (i.e. menarche) in rural Bangladesh occurring at age 13.0 years in 2017 [ 3 ], compared to age 15.8 years in 1976 [ 4 ].…”