Ovulation is an integral part of a woman’s menstrual cycle. Although it occurs about midway in the cycle, which begins on the first day of a woman’s period, it affects the entire cycle. However, this process can be split into an accelerated time of activity before an egg is released from an ovary, and a time of deceleration, after the egg or ovum is released.
As a woman begins her period, her body is in the follicular phase of the process. The body, or more specifically, the hypothalamus gland, recognizes this pre-ovulation state and releases hormones to the pituitary gland. On receiving these signals, the pituitary gland produces a hormone called follicle stimulating hormone (FSH), which will allow follicles in an ovary to start maturing into an egg.
During ovulation, generally only one egg is released. Even though several follicles along the ovaries may begin to mature, only one ovum actually will be released. The rest of the stimulated follicles simply disintegrate.
Once the follicles have produced a fully mature ovum, estrogen is released into the body. This signal that the body is ready to ovulate must be met by a hormone response from the hypothalamus and pituitary gland. They in turn release luteinizing hormone, which causes the egg’s release.
The release of estrogen and of luteinizing hormone tends to result in some women experiencing pre-menstrual syndrome (PMS). Women may also have cramping during this time, or notice a bit of spotting. The body temperature does rise slightly during this time period, and vaginal mucus becomes thicker. Many women may also feel the desire to be more sexually active prior to ovulation.
From a scientific standpoint, rise in body temperature, vaginal mucus and interest in sexual intercourse are all beneficial when one wants to produce a baby. They can help predict, depending upon the regularity of one’s cycle, when one is most likely to get pregnant.
Once the ovum is released and travels down one of the fallopian tubes, the process is complete and the body enters the luteal phase of the menstrual period. Estrogen and luteinizing hormone levels drop, and the body begins to produce progesterone. The uterus is lined with a thickened material that assists in egg implantation.
As progesterone is released, this lining will essentially thicken a bit more. However, the body also recognizes when the ovum is not fertilized and dissolves. Unfertilized ova tend to live for about 24 hours after the egg reaches the uterus. Some 12-16 days after a woman ovulates, this lining will be shed from the body at the beginning of a woman’s next menstrual cycle.
Although a woman's fertile time can sometimes occur on a predictable schedule, this is not always the case. Stress or illness can delay or force early ovulation, which can cause either late or early periods. Adding to the difficulty to pinpoint exact time of the egg is released and the window of fertility, it is important to note that male sperm can live for several days in the uterus. Pregnancy can occur if sexual intercourse takes place two to four days before the egg is released, and at least a day after ovulation.
Unlike the male sperm, a woman is born with all her immature egg cells. Male sperm, on the other hand, is manufactured on a rather constant basis. Lastly, although young women may not be aware of this, it is possible to get pregnant without ever having experienced one’s first menstruation. The cycle to mature an egg follicle and thus release the egg will occur before a woman has her first period.