13 Surprising Reasons for Early Menarche

Household instability, including divorce, conflict, and absent fathers, contributes to early menarche.

Source: Engin_Akyurt / pixabay

Girls are menstruating earlier and earlier. From 1840 to the 1990s, the age of menarche (the onset of menstruation) in developed countries fell from 16.5 to 13 years of age. Better nutrition is one obvious (and positive) reason for earlier menarche; however, some other causes are pernicious. Below are 12 surprising reasons for early menarche.

1. Plastics. Personal care and plasticizing chemicals (PCPPs), including phenols, parabens, and phthalates, have been linked to earlier menarche. These substances, which are widely used within consumer products, often operate as endocrine disrupters, either mimicking hormones or interacting with our hormonal systems. For example, prenatal exposure to phytoestrogens, which mimic estrogen, has been linked to early menarche.
2. Overnutrition. Overnutrition pertains to having excess nutrients, in this case, body fat. Body fat predicts earlier menarche, as fat signals to the body that there are sufficient resources to begin reproduction. Indeed, researchers have found that BMI and childhood obesity predict early menarche. This finding is generally consistent across cultures.
3. Rapid growth. Interestingly, some studies have linked rapid growth as an infant with earlier menarche. Other studies have found rapid pre-pubertal growth to be important. Yet other studies have identified an interaction between birthweight as an infant and in later childhood. Overall the research supports the energetics theory, which proposes that the availability of energy (e.g., body fat, nutrients) can induce earlier menarche.
4. Higher socioeconomic status (SES). Again, consistent with the energetics theory regarding the availability of nutrients, girls in higher SES households (based on factors like parents’ education status and occupation) tend to reach menarche earlier.
5. Stress. Stress at a young age has been found to cause early menarche. Researchers believe that stress causes young girls’ bodies to prioritize reproduction over long-term survival, thus resulting in menarche. This theory is termed the psychosocial acceleration theory. Yet, while early childhood stress is associated with early menarche, stress later on, such as during puberty, may result in later menarche, as the body may delay menarche until a better time.
6. Food insecurity. Food insecurity, or feeling anxious about the availability of food, was found to predict early menarche, especially for Black or Hispanic/Mexican girls compared to White girls. This effect was independent of nutrition and allostatic load, or stress-induced health issues. The researchers explain several possible mechanisms for this effect. First, in countries like the US, food insecurity can lead to overnutrition, given the intake of calorie-dense but imbalanced foods, such as fast food. Second, food insecurity can lead to psychological stress and allostatic load. In this study, researchers surprisingly found that girls with marginal food insecurity, as opposed to high, low, or very low food insecurity had earlier menarche. They theorized that households within this group might not be eligible for federal assistance, or that they are afraid of losing what they have.
7. Home instability/family conflict. Girls with household instability, including divorce, conflict, and absent fathers, tend to undergo menarche earlier, perhaps due to stress. Meanwhile, strong and supportive relationships with parents, especially fathers, predict later menarche.
8. Father figures. As I described in an earlier article, girls living with stepfathers or unrelated adult men have been found to reach menarche earlier. Possible reasons include stress and resulting body fat, shifts in reproductive strategies toward short-term strategies, and exposure to pheromones of unrelated men.
9. Mother’s psychopathology. Researchers found that the mother’s history of mood disorders predicted early menarche in girls. Furthermore, they identified two aforementioned reasons behind this relationship—stress and the presence of stepfathers or other unrelated adult men.
10. Trauma. Many studies have linked childhood trauma to early menarche. Early menarche has been documented among child refugees who were separated from their parents, internationally adopted children, and children who experienced sexual abuse.
11. Sibling relatedness. Girls with no siblings or only half/step-siblings reach menarche earlier than those with full siblings. The researchers posit that girls with related siblings may indirectly benefit (in terms of inclusive fitness) from helping their mothers and delaying their own reproduction. However, they mention that stress from gaining half-siblings/step-siblings or lack of social support from full siblings could contribute to earlier menarche.
12. COVID pandemic. As described in my prior article, the COVID pandemic may have contributed to earlier menarche through various mechanisms including sleep disturbance, Vitamin D deficiency, and COVID-19 infection.
13. Harsh mothers. In a longitudinal study of over 500 girls, researchers found that maternal harshness at age 4-5 predicted earlier menarche, which in turn predicted sexual risk-taking. These findings supported Belsky, Steinberg, and Draper’s evolutionary theory of socialization, which posits that difficult family conditions, including harsh parenting, cause girls’ bodies to speed up the reproductive process due to a seemingly precarious future.

Most of the underlying factors for early menarche are negative and often related to adverse childhood experiences or imbalances in one's diet/environment. Furthermore, early menarche has psychological and physical ramifications for girls, including a greater risk of psychiatric disorders, higher sexual risk-taking, and a higher likelihood of physical illnesses such as cancer. Negative consequences are long-lasting and persist into adulthood.

Given these findings, underlying causes like plastics and overnutrition should be directly addressed. In addition, future research should identify ways to support girls and women who went through early menarche, for example, by providing them with mentors and resources such that they can receive social support, avoid risky behaviors, and minimize negative mental and physical health consequences.