Menstrual Cycle
The menstrual cycle is the female body's monthly pattern of
preparing for a possible pregnancy. The uterus grows a new lining called the
endometrium; one of the ovaries releases an egg; and then, if the egg is not
fertilized by sperm, the endometrium sheds from the uterus as a menstrual
period.
- Menstrual phase (period). The thickened lining of the uterus (endometrium) is shed, causing
menstrual bleeding. Day 1 of the cycle is the first day of menstrual bleeding.
Bleeding usually lasts for 4 to 6 days.
- Follicular phase. The lining of the uterus thickens to prepare for pregnancy. Also,
inside a sac (follicle) on the surface of an ovary, an egg becomes ready to be
released.
- Luteal phase. The egg is released
(ovulation). Women's ovulation days can range from about day 7 to day 22 of the
cycle. But for an individual woman, the ovulation day is usually quite
consistent.
- If the egg is fertilized by sperm, it may
attach to (implant in) the lining of the uterus, and pregnancy begins.
- If the egg is not fertilized or does not implant, the lining of
the uterus is shed during the menstrual period, and the cycle starts
again.
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