During the normal menstrual cycle, the brain produces follicle stimulating hormone (FSH), which helps one of the eggs within the ovary grow and develop. During this process, the ovary produces estrogen to thicken the uterine lining, or endometrium. Once the egg has developed, the brain produces a large surge of luteinizing hormone (LH), which triggers release, or ovulation, of the egg from the ovary. The ovary then produces a hormone called progesterone which prepares the uterine lining for pregnancy. If pregnancy does not occur, then the progesterone levels fall and the uterine lining sheds. This shedding is referred to as menses or a period.
Ovulation, or the production of an egg, is required to achieve pregnancy. The best predictors of normal ovulation in women are regular menstrual cycles, occurring every 25-35 days, with menstrual flow of a regular length. Additional symptoms suggestive of ovulation are premenstrual breast tenderness and menstrual periods accompanied by crampy discomfort in the uterus. With regular menstrual cycles, ovulation typically occurs, 12 to 16 days before the onset of the period. These days, and the few days immediately preceding ovulation, are most critical for intercourse for conception to occur. When the male partner has normal sperm production, intercourse should occur every 24-48 hours during this time. There are a variety of ways to test for ovulation.
