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The average age of a girl's first period is 12 to 13 (12.5 years in the United States, [6] 12.72 in Canada, [7] 12.9 in the UK [8]) but, in postmenarchal girls, about 80% of the cycles are anovulatory in the first year after menarche, which declines to 50% in the third year, and to 10% by the sixth. [9]
Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty.Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. [5]
Diagram illustrating how the uterus lining builds up and breaks down during the menstrual cycle Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone ...
Menarche (/ m ə ˈ n ɑːr k i / mə-NAR-kee; from Ancient Greek μήν (mēn) 'month' and ἀρχή (arkhē) 'beginning') is the first menstrual cycle, or first menstrual bleeding, in female humans.
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
Seniors who turn 62 years old in 2025 are eligible for retirement, meaning individuals born in 1963 or later are eligible. While most may associate retirement with age 65, seniors can file for ...
For females, it is menarche, the onset of menstruation, which occurs, on average, between ages 12 and 13. [12] [23] [24] [25] The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well. [12] Regardless of genes, a girl must have a certain proportion of body fat to attain menarche. [12]
Primary amenorrhea is defined as an absence of secondary sexual characteristics by age 13 with no menarche or normal secondary sexual characteristics but no menarche by 15 years of age. [3] It may be caused by developmental problems, such as the congenital absence of the uterus, failure of the ovary to receive or maintain egg cells , or delay ...