When I was young, I heard somewhere that girls tended to begin menstruating when they reached 45kg in weight. I reached 45kg in weight when I was 13 3/4 and I began menstruating at that age, so for me at least that ‘fact’ seemed to hold true.
More recently I’ve become much more skeptical about whether girls really do need to reach a certain weight before they began menstruating. R. E. Frisch first came up with this “critical weight hypothesis“. He proposed that girls needed to reach a certain weight (around 47kg) before their bodies could begin to menstruate. It is an interesting theory, but research has proven that the “critical weight hypothesis” is wrong. Girls can begin menstruating at any weight, as long as they have enough fat on their bodies.
Although the critical weight hypothesis is wrong, researchers have continued to investigate the link between weight & height and menarche. These studies have found that height is a more important indicator of menarche than weight. According to one study in Taiwan, there is no change in weight velocity at the age of menarche, but there is with height: “height velocity reaches a peak 1 year before menarche but height velocity stopped increasing within 1 year after menarche.”
This is interesting. I just had a look at my gr
owth chart & it seems to be consistent with the findings of this Taiwanese study. My growth rate really slowed down after menarche: it went from 6cm/year in the two years before menarche to 2cm/year in the two years post menarche. My weight, however, didn’t seem to be connected to my menarche age at all.
Other physical indicators of menarche:
“Menarche usually occurs about two years after your breasts develop (thelarche) and between 4 and 6 months after the growth of your pubic and underarm hair.” I can’t remember when my pubic/underarm hair began to grow,
but that is interesting! I do remember that my breasts began developing when I was eleven, a couple of years before I got my first period.
My hips began to widen at almost the exact same time as I began menstruating. I wonder whether hip growth is a sign that menarche is coming (or can hips widen at any time)?
Psychosocial effects of early puberty:
Girls who go through puberty early tend to get lower marks at school & have lower self-esteem than their peers (perhaps because girls who develop early are quickly sexualised and more likely to be shamed ‘sluts’). In contrast, boys who are early developers do well at school & have higher self-esteem than their peers (perhaps because they are looked up to by their peers and can ‘get’ the girls more easily). Both girls and boys who develop early are exposed to more risks than late-developers (eg. early se
xual activity, alcohol & drugs).
Psychosocial and physical effects of early menarche:
At age 15-16, girls with menarche before age 11 (early) were more norm-breaking, including being delinquents. In addition, they had earlier advanced sexual experiences. Early-developed women had lower academic education. At age 43, women with early menarche were shorter and heavier, had worse physical fitness and dieted more frequently compared to other women. There was no difference in quality of life.
Early menarche is related to adult height: Research has shown that girls who go through menarche early tend to be shorter than girls who go
through menarche later: “The daughters of short women matured early and continu
ed growing heavier, but they stopped growing taller and were overtaken in height by the later-maturing daughters of tall women.” Another study found the same results: ““Our results support the general belief that women who reach their menarche at a later age will eventually grow taller compared with women who reach their menarche at an earlier age. A delay in menarche allows more growth of the long bones before the epiphyses unite and results in a taller adult height… for each year of delay in when a woman reaches menarche, she will grow approximately 0.35 cm taller in total body height.”