The menstrual (monthly) cycle - the periodic uterine bleeding is one of the key physiological functions of the female body. Ovulation is release of a matured egg from the ovary. During ovulation if the egg does not get fertilized (does not meet the sperm), it disintegrates and is released along with the inner lining of the uterus, (endometrium) causing bleeding. This process is known as menses or menstrual period.

Menstrual cycle (Time between two periods) usually averages 28 days in length with normal variation ranging from 21 to 35 days. The day a period starts is counted as day 1 of the menstrual cycle. When the two -seven days of your period are over, the ovary begins ripening another egg ready for release during the next ovulation. Meanwhile the uterus begins to build up another inner lining ready to receive the fertilized egg.

Ovulation normally occurs fourteen days before beginning the next period, regardless of the length of the cycle. So a woman with a 28 day cycle would tend to ovulate on day 14. The woman with a 32 day cycle would tend to ovulate on day 18 (32-14). The life time of the egg is brief -only 24 hours. So to get pregnant the sperm should reach the egg during this fertility period.