Menstrual cycle is the cycle of changes that occurs in the uterus and ovary for the purpose of sexual reproduction. It is essential for the production of eggs and for the preparation of the uterus for pregnancy. The menstrual cycle occurs only in fertile female humans and other female primates.
In humans, the length of a menstrual cycle varies greatly among women (ranging from 25 to 35 days), with 28 days designated as the average length. Each cycle can be divided into three phases based on events in the ovary (ovarian cycle) or in the uterus (uterine cycle). The ovarian cycle consists of the follicular phase, ovulation, and luteal phase whereas the uterine cycle is divided into menstruation, proliferative phase, and secretory phase. Both cycles are controlled by the endocrine system and the normal hormonal changes that occur can be interfered with using hormonal contraception to prevent reproduction.
Human reproduction is any form of sexual reproduction resulting in the conception of a child, typically involving sexual intercourse between a man and a woman. During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the woman's ovum by the man's sperm, which after a gestation period is followed by childbirth. The fertilization of the ovum may nowadays be achieved by artificial insemination methods, which do not involve sexual intercourse.
The relationship between culture and menstruation is expressed in many ways. A variety of menstrual-related traditions exist. One group of authors has even theorized that menstruation may have played a key role in the development of symbolic culture in early human society.
Historically, a menstruating woman was considered sacred and powerful, with increased psychic abilities, and strong enough to heal the sick According to the Cherokee, menstrual blood was a source of feminine strength and had the power to destroy enemies. In Ancient Rome, Pliny the Elder wrote that a menstruating woman who uncovers her body can scare away hailstorms, whirlwinds and lightning. If she strips naked and walks around the field, caterpillars, worms and beetles fall off the ears of corn. Menstrual blood is especially dangerous to men's power. In Africa, menstrual blood is used in the most powerful magic charms to both purify and destroy.
A menstrual taboo is any social taboo concerned with menstruation. In some societies it involves menstruation being perceived as unclean or embarrassing, extending even to the mention of menstruation both in public (in the media and advertising) and in private (amongst friends, in the household, and with men). Many traditional religions consider menstruation ritually unclean.
Different cultures view menstruation differently. Studies in the early 1980s have shown nearly all girls in the USA believed that girls should not talk about menstruation with boys, and more than one-third of the girls did not believe that it was appropriate to discuss menstruation with their fathers. The basis of many conduct norms and communication about menstruation in western industrial societies is the belief that menstruation should remain hidden.