A regular concern for most women is the time when they get their periods. This is the day when the monthly menstrual cycle ends and bleeding occurs from the vagina. The whole menstrual cycle is caused by an intricate interplay of various female hormones that prepare a woman’s body for a possible pregnancy. The entire cycle usually lasts for about a month, and involves cyclic changes in the ovary and the uterus.
Women who want to plan their pregnancy are also concerned about the time of ovulation. This is the time during the middle of the menstrual cycle when a mature egg is released from the ovary. There is a small window of about 24 hours around the time of ovulation when pregnancy is most likely to occur. Determining the time of ovulation during a menstrual cycle is important for women who either want to get pregnant or avoid getting pregnant. However, the determination of the exact time of ovulation is not always possible. Miscalculations do happen.
Read more on the menstrual cycle.
Ovulation and Pregnancy
Ovulation typically occurs about 12-16 days prior to menstruation. A woman is fertile only during the short time period when the egg is released from the ovary. If not fertilized by a sperm, the released egg degenerates within 24 hours. Therefore, for pregnancy to occur, the timing of the intercourse should coincide with the time of ovulation. If fertilization does occur, the next period does not occur. However, certain factors need to be considered when trying to determine the exact time of ovulation.
Pregnancy does not require intercourse and ovulation on the same day
Even though a mature egg that is released from the ovary is viable only for a period of about 24 hours, the sperms can survive in a woman’s reproductive tract for up to 5 days. This means that a woman can get pregnant even if she has intercourse a few days prior to the day of ovulation.
However, many women tend to believe that pregnancy is possible only if intercourse happens on the day of ovulation. This fact has significance for women who want to conceive as well as for women who want to have intercourse without getting pregnant.
Ovulation may not occur with every menstrual cycle
Not all women tend to ovulate in each menstrual cycle. Some women can also have menstrual cycles without ovulation. Such menstrual cycles are technically referred to as anovulatory cycles. Women who are not able to get pregnant may have anovulatory cycles for many months or years.
In such cases, trying to match the timing of the intercourse with the estimated date of ovulation is fruitless as pregnancy cannot occur in the absence of the egg. It is important to note that women with anovulatory cycles may have regular monthly periods. In the case of anovulatory cycles, medical attempts at inducing pregnancy may include stimulation of ovulation or treating the underlying cause of anovulation.
Calculation of the exact date of ovulation is not always possible
Calculating the date of ovulation is not an exact science. The date of ovulation varies even in women who have very regular menstrual cycles. Therefore, there is always some uncertainty in the estimated date. This uncertainty is higher in women who have irregular menstrual cycles. In such cases, trying to determine the date of ovulation using the calendar method may not be successful. One may need to pay attention to the symptoms of ovulation or conduct tests for ovulation in order to determine the date of ovulation with any degree of certainty. It is important to note that women on hormone-based contraceptives have regular periods but no ovulation.
Signs and Symptoms of Ovulation
No one method is sufficient to accurately determine the exact date of ovulation. Therefore, multiple methods should be used to increase the chances of an accurate estimate of ovulation. Paying attention to the signs and symptoms of ovulation may help.
However, it must be stressed that the signs and symptoms of ovulation are not very clearly defined, and women may imagine a symptom of ovulation where none exists. The identification of such signs and symptoms is a subjective matter. Despite this drawback, it may be worth considering some of the signs and symptoms that may accompany the process of ovulation.
Rise in basal body temperature
Ovulation may raise in the basal body temperature slightly. This change is about 0.4-0.6 °F, and is not detectable without the aid of a good thermometer. Special thermometers for measuring basal body temperature are available.
Changes in cervical mucus
There are certain changes in the characteristics of cervical mucus that may signal the time of ovulation. Just prior to ovulation, the cervical mucus changes from a cloudy and sticky consistency to a clear and slippery consistency (resembling raw egg white). Ovulation is also accompanied by a substantial increase in the amount of cervical mucus.
Ovulation may also cause pain in some women. This typically occurs in the middle of the menstrual cycle and may last from a few minutes to a few hours. Pain caused by ovulation (also known as Mittelschmerz or mid-cycle pain) usually affects one side of the abdomen.
Read more on mid-cycle pain.
Home and Laboratory Tests for Ovulation
The time of ovulation can also be determined by a variety of medical tests. Some of these tests can be conducted within homes, whereas others need to be conducted in a laboratory by a trained medical professional. The following are some of the tests that are frequently used to test for ovulation.
- Urine test: Just prior to ovulation, the level of luteinizing hormone (abbreviated as LH) increases significantly in the blood and urine. This hormone can be detected in the urine by using commercially available home ovulation predictor kits.
- Saliva test: Like luteinizing hormone, the level of estrogen hormone also increases significantly just prior to ovulation. This increase in estrogen level can be detected in the saliva by using an ovulation predictor kit.
- Blood test: After ovulation, the level of progesterone hormone in the blood increases. This increase in the level of progesterone can be detected accurately through blood tests.
- Ultrasound scan: A skilled medical practitioner can use daily ultrasound scans of the abdomen to check the development of the primary follicle as it matures and ruptures to release an egg into the fallopian tube.
- Biopsy: A biopsy of the endometrial tissue is done only on rare occasions to verify the changes caused by the increase in progesterone levels after ovulation.