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Many cultures surround the onset of menstruation with taboos,
rituals and myths. Some societies consider menstruating women
"unclean", believing that they may turn food bad or damage crops,
isolating them for the first three to five days of the menstrual
flow. Fortunately, Western society ignores those myths, however,
many still believe that women should avoid showering, abstain from
intercourse or refrain from swimming, while menstruating. While
there is no medical indications against it, some studies show
increased risks of pelvic inflammatory disease (PID), endometriosis,
and sexually transmitted diseases (STDs) in women who have sex while
menstruating.
THE MENSTRUAL CYCLE
The age at which a girl starts menstruating varies - anything from
the age of 9 up to the age of 17 is considered normal, however, most
girls have started by the time they reach 14. The onset of
menstruation marks the official entry into womanhood - the beginning
of the ability to bear children.
The basis of a woman's reproductive capacity - the ovaries and their
supply of eggs (ova) - is set aside way before birth. The miniature
ovaries of the developing female embryo contain approximately 5-7
million immature eggs. At birth, this number drops significantly,
with about two million eggs remaining in the newborn girl's ovaries.
During childhood, more eggs disintegrate, leaving only approximately
300 000 eggs at the onset of menstruation. The woman's egg supply is
further depleted during her child-bearing years, some, before ever
reaching full maturity, let alone being fertilized.
After the onset of menstruation (menarche), one egg ripens inside
one of the ovaries (on a monthly basis), within an ovarian follicle
(sac), under the influence of female hormones. The ovum is then
released, and travels down the fallopian tube towards the uterus.
If, on this 'journey', the egg is not fertilized, menstruation
ensues, whereby the egg and uterine lining (endometrium) are
sloughed off and the cycle begins once again.
The average duration of a normal menstrual cycle varies from
short (21 days) to long (35 days), the norm being 28 days, with
blood losses averaging 30-60ml.
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