Tests for Determining Ovulation Date
Ovulation tests assist women in determining their fertile period, typically by detecting hormonal changes indicating the release of an egg from the ovary. These tests can be conducted using urine or saliva samples. Urine tests primarily detect the surge in luteinizing hormone (LH), which precedes ovulation, while saliva tests monitor changes in estrogen levels, which also increase around ovulation.
A positive result in these tests usually indicates that ovulation is imminent, occurring approximately 24-36 hours after the surge in LH or the increase in estrogen is detected. However, it's important to note that these tests should not be relied upon as a sole method of contraception, as they cannot guarantee the absence of fertility. Additionally, while they can help identify the most fertile days in a woman's menstrual cycle, they do not provide a definitive assessment of the likelihood of pregnancy.
Ovulation, which is the release of an egg from the follicles in the ovaries, normally occurs in the middle of each menstrual cycle. Ovulation tests that women can do at home are used to determine the ovulation date, increasing the chances of pregnancy by timing intercourse close to this day. To understand how at-home ovulation tests work, it's necessary to know how ovulation occurs and how the menstrual cycle progresses each month.
How does ovulation (egg release) and the menstrual cycle occur?
The day when menstrual bleeding begins marks the start of a menstrual period (cycle), which typically lasts about a month. (The menstrual cycle refers not only to the days of bleeding but also to the entire period from the first day of one period to the first day of the next.) At the beginning of this period, the FSH hormone, secreted from the pituitary gland in the brain, increases and gradually stimulates the growth of the egg. As the egg follicle grows, it secretes estrogen hormone, which, like FSH, increases progressively. By the middle of the menstrual cycle (i.e., around 14 days after the start of menstruation), FSH and estrogen levels peak, and at the same time, there is a sudden increase in LH hormone secretion from the pituitary gland. This sudden rise in LH hormone (LH surge) is the main mechanism that triggers ovulation. Ovulation occurs 24-36 hours after the LH surge. Ovulation tests done with urine detect this LH surge. Tests done with saliva are based on the increase in estrogen. After ovulation, estrogen, FSH, and LH hormones decrease, while progesterone hormone levels begin to rise. After ovulation, the follicle containing the egg turns into the corpus luteum, releasing progesterone from there. If pregnancy does not occur, the subsequent decrease in progesterone will initiate a new menstrual bleeding. If pregnancy occurs, progesterone will sustain the pregnancy in the uterus and continue to be secreted without decreasing.
Ovulation (egg release) test in urine (LH test):
The urine-based ovulation test detects the increase in LH hormone described above. When LH hormone levels rise in the blood, they also appear in the urine. To detect this LH increase, the test should be done daily in the days leading up to ovulation. For women with regular monthly cycles, the test can start 12 days after the onset of menstruation and continue for 5 days. However, for women with different cycle lengths, the timing of the test will vary. Refer to the table on the right for this. For example, for those with a cycle length of 35 days, they should start the test counting from the first day of menstruation and start on day 18, testing for 5 days. This is because ovulation will occur later in these women. Ovulation typically occurs approximately 14 days before the onset of menstruation. Predicting ovulation day in women with highly irregular periods is challenging, and in such cases, consulting a doctor is recommended regarding when to start the test.
How to use an ovulation test kit?
The procedure for using the tests may vary depending on the brand. In some, the test stick (ovulation kit) is dipped into a container of urine, while in others, it is held in the urine stream while urinating. The instructions for conducting and interpreting the test are detailed on the product's packaging, and they should be followed carefully. It's not advisable to use the first-morning urine for the test, as it can be misleading. Subsequent urine samples can be used. Alcohol, cigarettes, antibiotics, painkillers, suppositories (ovules), etc., do not affect the test, but medications used for ovulation induction, such as hormone injections (trigger shots), can affect or mislead the test. Drinking excessive water and fluids can dilute the urine, reducing the LH concentration, leading to a false negative result. Therefore, it's recommended not to consume excess fluids 2 hours before taking the test.
When the ovulation test yields a positive result:
Depending on the brand, typically, two pink lines indicate a positive test, indicating that ovulation will occur, while a single line indicates no ovulation on that day. If the test is positive (meaning LH surge is detected), it indicates that ovulation will occur approximately 24-36 hours later. In this case, it's advisable to have intercourse 24 hours after administering the ovulation test. This is because ovulation occurs 24-36 hours after the LH surge, and the egg cell can live for about 24 hours. Sperm can live for an average of 3 days, while a woman's egg can survive for about 1 day. Therefore, pregnancy can occur even if intercourse doesn't happen on the exact ovulation day. For example, in a woman who will ovulate on the 10th of the month, pregnancy can occur even if intercourse happens on the 7th or 8th because sperm can survive for 3 days. Similarly, intercourse on the 11th can result in pregnancy because the egg cell can survive for 24 hours. Hence, there's a window of about 5 days before and after ovulation when a woman can conceive. Pregnancy is not possible on other days, even if intercourse occurs.
Note: Ovulation tests cannot be used as a contraceptive method.
It's impossible to determine safe days for intercourse and prevent pregnancy solely based on ovulation tests. This is because the days of potential pregnancy vary due to the survival times of sperm and the egg. For example, pregnancy can occur based on intercourse that happened before taking the test.
Ovulation Test (Ovulation Predictor Kit) When to Do?
If the normal menstrual cycle occurs every 28 days, ovulation typically occurs within 10 to 14 days before the onset of menstruation. If the menstrual cycle lasts around 28-32 days on average, ovulation usually happens between the 11th and 21st days.
An ovulation test can be done at any time of the day, but more reliable results are often obtained in the morning. If the ovulation test results positive, it is considered an indication of being in the ovulation period, and if sexual intercourse takes place within 24 hours, the chances of pregnancy increase.
Ovulation tests using saliva:
These tests rely on detecting the increase in estrogen hormone during the mid-cycle days, as described earlier. They are not as practical as urine tests and are not as widespread.
Detection of ovulation (egg release) through blood tests or ultrasonography:
LH hormone levels can be measured in the blood, and ovulation can be predicted based on its elevation, although this method is not commonly used. Instead, ultrasonography can indicate ovulation when the egg has grown to a certain size. Ovulation occurs when the egg (follicle) size reaches approximately 18-20 mm. Additionally, a high progesterone level measured in the blood one week after ovulation (on the 21st day of the cycle) confirms ovulation for that month when necessary. Sometimes, fluid in the abdomen and the area where ovulation occurred can be seen on ultrasound shortly after ovulation, but this is not always feasible.
Luteinizing Hormone (LH) Level Measurement with Urine Test Kits:
Various ovulation detection tests are available at pharmacies, typically utilizing test strips that show changes in LH levels in urine. Ovulation generally occurs within 12 to 36 hours after the LH surge. Urine testing usually begins around two days before the expected ovulation day. In women with a 28-day menstrual cycle, ovulation typically occurs between days 13 and 15. For women with irregular periods, urine testing should be timed based on the earliest and latest possible ovulation days. If menstrual cycles occur every 27-34 days, ovulation usually happens between days 13 and 20. Therefore, testing should start on day 11 and continue until ovulation is detected or until day 20. The chance of detecting ovulation with a 5-day test is 80%, while it increases to 95% with a 10-day test. Once ovulation is detected, there's no need to continue testing. Sometimes, ovulation may not occur.
If ovulation is not detected over two or more consecutive menstrual cycles, there may be an ovulation issue.
Hormone LH Level Measurement with Blood Tests:
Elevated progesterone levels in the blood are typically observed alongside ovulation. A blood test for progesterone measurement can be conducted approximately one week before the expected start of the next menstrual period. The LH surge occurs just before ovulation. The LH level in the blood or urine can be measured to determine when the follicle will mature and be ready for ovulation. Estrogen is secreted by the developing follicle and rapidly rises just before ovulation. If ovulation is induced with medication, frequent measurement of estrogen levels may be necessary to determine follicular development.
Ovulation Calculation
To calculate ovulation, it's necessary to know the time intervals of the individual's menstrual cycle. If the menstrual cycle occurs every 28 days, ovulation is expected to happen approximately 14 days before the start of the next menstrual period. Therefore, the number of days between two menstrual cycles provides the correct estimate for ovulation.
Ultimately, ovulation tests serve as a useful tool for couples trying to conceive by providing guidance on the timing of intercourse to maximize the chances of pregnancy. However, they should be used in conjunction with other fertility awareness methods for a more comprehensive approach to family planning.
In couples seeking to conceive, ovulation disorders, also known as ovulatory dysfunction, which affect approximately 15% of cases, can be a contributing factor. These disorders can range from severe (anovulation) to mild (oligo-ovulation) and may hinder pregnancy.
The presence and timing of ovulation can be determined through various methods, all of which rely on the hormonal events of a normal menstrual cycle. Some tests are simple, while others are complex and costly. However, no test can definitively confirm ovulation; pregnancy remains the only conclusive evidence.
