Ovulation Changes and Why They Occur

Most menstrual cycles last between 28 and 32 days. Ovulation typically occurs about midway through the menstrual cycle. While there is significant variation between each person, most people can predict ovulation by counting about 14 days from their last menstrual period. The days surrounding ovulation, 10 through 18, are the most fertile phase.

Because estrogen levels spike at the end of the follicular phase of the menstrual cycle, ovulation begins with a surge of hormones in response. Follicle-stimulating hormones cause follicles in the ovary to mature. After a few days, another surge of luteinizing hormones interact with the developing follicle, causing it to release an egg. It takes roughly five days for the egg to travel through the fallopian tube to the uterus. During this time, progesterone hormone levels also rise. These hormones are responsible for many of the physical changes ovulation causes.

macniak / Getty Images

One of the main observable signs of ovulation is a change in vaginal discharge. Just before ovulation occurs, there is often an increase in clear, viscous, wet vaginal secretions that some people compare to raw egg whites. After ovulation, the amount of mucus diminishes and becomes thicker, cloudy, and much less noticeable.

It is possible to track ovulation by observing the cervix, which is the lower section of the uterus. As ovulation approaches, the normally firm cervix softens and rises in response to the high levels of estrogen. Some people can determine their cervix position themselves by inserting a finger into their vagina. Others may need the assistance of a fertility clinic or OB/GYN.

Another potential sign of ovulation is a change in body temperature while at rest, also known as the basal body temperature. During ovulation, the basal body temperature often increases slightly in response to the increase of progesterone. Special thermometers can specifically measure basal body temperature and track the results. By measuring daily, a person can more easily determine when they are ovulating.

Some people feel ovulation as a lower-abdominal pain. This pain, called mittelschmerz, can last for several minutes to a few hours. In some cases, it continues for a few days. For some individuals, mittelschmerz feels like typical menstrual cramps, while others describe it as a sharp, sudden pain. Mittelschmerz pain occurs on the side of the ovary that is releasing the egg.

In addition to the more typical signs of ovulation, some people have more unique responses to ovulation. For example, the woman may notice that ovulation heightens their sense of smell. Additionally, sexual desire may increase significantly in the days leading up to ovulation. Small studies have also tied changes in body odor, facial attractiveness, and sexual behavior to ovulation.

It is possible to identify when a woman is ovulating by checking these levels. Ovulation predictor tests are similar to pregnancy tests, but they detect the lutenizing hormone rather than human chorionic gonadotropin, a pregnancy hormone. Using a urine sample, the predictor kits test for a surge of luteinizing hormone. If the surge is present, the strip changes color and the user knows they are likely ovulating.Often, women who are trying to get pregnant use these tests daily.

A more costly option for people who want to track their ovulation is a fertility monitor. This is an electronic device that can analyze hormone changes, basal body temperature, or the electrical resistance of saliva or vaginal fluids. There is a lack of evidence on the effectiveness of tracking ovulation in any way, so there is some debate as to whether the more costly monitors are worth the investment.

Ovulation typically occurs once per menstrual cycle. However, certain disorders may change the frequency of ovulation. Oligoovulation is infrequent or irregular ovulation, usually appearing as cycles lasting over 36 days or fewer than eight cycles each year. Some people ovulate two or three times each menstrual cycle. It is also possible for the ovaries to release more than one egg at a time.