Understanding the onset of puberty

The average age of menarche, or the commencement of menses (menstruation), globally is 12 years of age¹ and is influenced by a number of factors including nutritional, metabolic, genetic and environmental influences with studies identifying a continuous decline in menarche age.²

A higher menarche age for a country correlates with increased fertility, with industrialised countries demonstrating a decline in menarche age, potentially associated with the rise in obesity in these countries.¹ Socioeconomic status in the United States has also been connected with menarche, with lower socioeconomic levels associated with younger onset of menarche, however, further studies on this variable need to be undertaken.¹

Developmental signs

Pubertal development is characterised into stages based on thelarche (breast budding) and breast growth and menarche.³

The role of hormones

Growth spurts that occur during puberty are regulated by the increased gonadal sex steroids, growth hormones (GH), IGF-I and insulin.⁴ IGF-I and GH regulate protein and energy use, while insulin levels increase during puberty.⁴ Serum luteinising hormone, follicle stimulating hormone and estradiol levels correlate to menarche.³ Gonadotrophins and estradiol levels increased through the stages of puberty including a follicle stimulating hormone peak at puberty stage 3, with overweight and obese girls identified as having paradoxically reduced gonadotrophin levels suggesting a reduction of the hypothalamic-pituitary-gonadal axis caused by adiposity.³

Early menarche

Studies have demonstrated that early menarche, defined as onset earlier than 12 years of age, has a negative impact on adult body mass index.⁵ Connection between weight status at the time of thelarche and menarche has been made, with overweight or obese girls reaching menarche earlier than normal or underweight girls.²

Early onset menarche is associated  with low birth weight, infantile malnutrition and rapid infancy growth suggesting that metabolic imprinting may be involved⁵ and increasing the risk of non-communicable diseases, higher body fat and leptin resistance with advancing age.⁴

Early and later than average onset of thelarche and menarche is also connected to a shorter height in girls which is associated with a potential for reduced respiratory function due to decreased lung volume.⁶ A connection between increased body mass index (BMI) and early thelarche and menarche age and height was also connected.⁶ It has been hypothesised that the reduction in height with early menarche correlates with estradiol levels increasing at menarche, prompting the epiphyseal plate closure of the bones.⁶ 

Long term implications of early onset of menarche may include an increased risk of the development of endometriosis.⁷ All cause mortality is inversely related to the age of menarche with a 3% decline in risk associated with each year of advancing age at menarche, even with adjustments made for adult BMI.⁵ Premature menopause and poor mental health may be associated with early onset menarche.¹

As a clinical nutritionist, I am passionate about the health of my paediatric patients, working for their health today, and in the future.

References

1. Canelón, S. P., & Boland, M. R. (2020). A systematic literature review of factors affecting the timing of Menarche: The potential for climate change to impact women’s health. International Journal of Environmental Research and Public Health, 17(5), 6–13. https://doi.org/10.3390/ijerph17051703 
2. Jaruratanasirikul, S., Chanpong, A., Tassanakijpanich, N., & Sriplung, H. (2014). Declining age of puberty of school girls in southern Thailand. World Journal of Pediatrics, 10(3), 256–261. https://doi.org/10.1007/s12519-014-0472-2
3. Khadgawat, R., Marwaha, R. K., Mehan, N., Surana, V., Dabas, A., Sreenivas, V., Gaine, M. A., & Gupta, N. (2016). Age of onset of puberty in apparently healthy school girls from northern India. Indian Pediatrics, 53(5), 383–387. https://doi.org/10.1007/s13312-016-0857-5 
4. Soliman, A., De Sanctis, V., & Elalaily, R. (2014). Nutrition and pubertal development. Indian Journal of Endocrinology and Metabolism, 18, S39–S47. https://doi.org/10.4103/2230-8210.145073 
5. Charalampopoulos, D., McLoughlin, A., Elks, C. E., & Ong, K. K. (2014). Age at menarche and risks of all-cause and cardiovascular death: A systematic review and meta-analysis. American Journal of Epidemiology, 180(1), 29–40. https://doi.org/10.1093/aje/kwu113 
6. Yousefi, M., Karmaus, W., Zhang, H., Roberts, G., Matthews, S., Clayton, B., & Arshad, S. H. (2013). Relationships between age of puberty onset and height at age 18 years in girls and 
7. Treloar, S. A., Bell, T. A., Nagle, C. M., Purdie, D. M., & Green, A. C. (2010). Early menstrual characteristics associated with subsequent diagnosis of endometriosis. American Journal of Obstetrics and Gynecology, 202(6), 534.e1-534.e6. https://doi.org/10.1016/j.ajog.2009.10.857