irth weight and childhood obesity are the other mechanisms that partly explain the difference in age of menarche and the onset of the regulatory cycle in various races.
Harlow et al. reported that menstrual cycles longer than 45 days were 1.86 times more in European-American adolescents than in African-American adolescents
The results of a cohort study on the Iranian population showed that the menarche age of girls was significantly correlated with the menarche age of their mothers
Therefore, it seems that genetic and familial factors influence the timing of the onset of menstrual cycle regulation through neuroendocrine pathway development and genes associated with hyperandrogenism.
adolescent girls of the Asian/Pacific Island races usually experience menarche earlier than their non-Hispanic white counterparts
Cigarette smoking disrupts the placental blood flow (68) and may induce an adverse toxic effect on the ovaries (69). In a cohort study by Dossus et al., childhood exposure to cigarettes was associated with the increased interval between menarche and menstrual cycle regulation (29).
n this regard, a study on female adolescents showed that girls born in summer experienced earlier menarche than females born in other seasons (35). A
Living in mountainous areas and cold climates may affect menarche age in adolescents (74, 75). Climate change can affect menarche age by affecting food availability and increasing exposure to air toxins or pollutants (76).
It has been shown that pre-pubertal intake of milk, but not cheese and yogurt, may reduce the age at menarche (77).
Another aspect of the lifestyle is sleep. In this regard, Nam et al. conducted a population-based study on 801 Korean adolescents (41). They observed that sleep duration less than five hours per day was associated with menstrual irregularities (41).
Stress is one of the most important health disorders in today's world. Several studies demonstrated the adverse effects of various stressors during childhood and early adulthood on the interval between menarche and the onset of menstrual regularity (79, 80).
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