what is the average age to start menstruating
Menarche Girls experience menarche at different ages. The timing of menarche is influenced by female biology, as well as genetic and environmental factors, especially nutritional factors. The mean age of menarche has declined over the last century, but the magnitude of the decline and the factors responsible remain subjects of contention. The worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics. Various estimates have placed it at 13.[1] Some estimates suggest that the median age of menarche worldwide is 14, and that there is a later age of onset in Asian populations compared to the West.[2] The average age of menarche is about 12.5 years in the United States,[3] 12.72 in Canada,[4] and 12.9 in the UK.[5] A study of girls in Istanbul, Turkey, found the median age at menarche to be 12.74 years.[6]
Embryo In humans, a pregnancy is generally considered to be in the embryonic stage of development between the fifth and the eleventh weeks after fertilization,[1] and is expressed as a fetus from the twelfth week.
Menopause Before menopause, a woman's periods typically become irregular,[11] which means that periods may be longer or shorter in duration or be lighter or heavier in the amount of flow.[11] During this time, women often experience hot flashes; these typically last from 30 seconds to ten minutes and may be associated with shivering, sweating, and reddening of the skin.[11] Hot flashes often stop occurring after a year or two.[8] Other symptoms may include vaginal dryness, trouble sleeping, and mood changes.[11] The severity of symptoms varies between women.[8] While menopause is often thought to be linked to an increase in heart disease, this primarily occurs due to increasing age and does not have a direct relationship with menopause.[8] In some women, problems that were present like endometriosis or painful periods will improve after menopause.[8]
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