female menstruation

Puberty - The arrival of the monthly “friend”. The principle sign that a girl has become sexually mature and is capable of reproduction is the onset of menstruation, a period of cyclic bleeding from the vagina. (Smith 1997, pg 217) This is one of the key physiological functions of the female body. An ovarian, or estrus, cycle is characteristic of all female mammals, but menstruation, periodic uterine bleeding that accompanies the ovarian cycle, occurs only in women, …

…is unusual. In terms of conception, fertility depends on three factors: a healthy egg, healthy sperm, and favorable cervical mucus. A woman ovulates once a cycle. The egg lives twelve to twenty-four hours and then disintegrates if not fertilized. Under favorable cervical mucus conditions (cervical mucus nourishes and guides the sperm, which would otherwise die in about a half-hour or never reach the egg), sperm can survive as long as five days within the body.