Let’s try calculating ovulation days

After getting married, going on a honeymoon, and spent some time together as husband and wife, couples may be ready to finally have a baby to complete their family.

They have prepared their bodies, exercised, and taken vitamins to prepare for pregnancy. They wanted to conceive as soon as possible and heard that the best chance is on the day of ovulation. They have heard that if they count 7 days after the last period, it is the highest chance to conceive. They also want to know how to determine the day of ovulation, such as counting days or observing physical signs. They have heard that if they count 7 days after the last period and don't conceive, they may not be able to conceive that month. They also want to know how to conceive during the middle of the cycle, but they are unsure about the timing. They have heard that the middle of the cycle is around day 15 of the menstrual cycle. They may have difficulty understanding and would like some help to determine the day of ovulation. Let’s get into how the couple can ‘calculate’ their ovulation days.

To determine the day of ovulation, there are several methods, but the easiest and first method is to count the days from the start of the menstrual cycle. First, you need to look back at the menstrual history for at least 3-6 months. The longer the history you have, the more accurate your calculation will be. Count the days from the first day of the period, whether it is fresh blood, dark blood, or spotting. The first day of the period is counted as day 1, and you continue counting until the day before the next period starts, which is day 1 of the next menstrual cycle. The number of days counted becomes the length of one menstrual cycle. For example, if the period started on June 14th and came again on July 12th, the cycle length is 28 days. If the period started on June 14th and came again on July 4th, the cycle length is 20 days. If the period started on June 14th and came again on July 31st, the cycle length is 47 days.

After calculating for 3-6 months, you can determine the length of your menstrual cycle, which is typically between 28-30 days. If a person has a shorter or longer cycle, it may affect the timing of ovulation. Ovulation usually occurs around 14 days before the next period starts, but it can vary from person to person. There are also physical signs of ovulation, such as changes in cervical mucus and basal body temperature. If you want to conceive, it is best to have intercourse a few days before ovulation and on the day of ovulation itself.

If the menstrual cycles are irregular, what should be done? In this case, it will be a little more difficult. You have to subtract 14 from the shortest cycle and the longest cycle. For example, if the shortest cycle is 24 days and the longest is 40 days, the result is 10 and 24. This means that ovulation will occur between days 10-24 of the menstrual cycle, which is a relatively wide range. It is not certain which day within these 15 days (10-24) ovulation will occur, so it is recommended to have intercourse every other day or count every even day (10, 12, 14, 16, 18, 20, 22, 24) or odd days (13, 15, 17, 19, 21, 23, 25).

If the menstrual cycles are very far apart and differ greatly each month, it will be even more difficult. Some people say that they cannot follow what the doctor recommends. Some count every 7-8 days apart per month, while others who follow the recommendations have to do it for more than ten months per cycle. If they still cannot conceive, they have to do it all over again for several months.

Therefore, if you want to reduce the margin of error in counting days, you need a little help. The easiest way to do this is to use an LH ovulation test kit. Nowadays, there are kits that can detect ovulation, which look for the luteinizing hormone (LH) in urine. Normally, the body releases a small amount of LH hormone until just before ovulation. LH hormone levels will increase rapidly and ovulation will occur within 12-48 hours.

Using an ovulation test kit is very easy. Just check with urine, starting on the day when ovulation is expected to occur, such as the example above for people with irregular cycles. The ovulation period is estimated to be around days 10-24. You can use the ovulation test kit to detect when the LH hormone level is high and ovulation is about to occur, then plan to have intercourse during this time to increase the chances of conception.

The general types of test kits available for sale are as follows:

Strip Test: When removing the test kit from the package, immerse the test strip with the arrow end into a urine cup for about 5 seconds. Place the test strip flat and clean and wait for about 5 minutes before reading the result. The general test kit comes with 20 sheets, priced at around 300-370 baht, while the iBabi brand has 5 sets per box, priced at around 170-190 baht.

Cassette Test: When removing the test kit from the package, place the cassette flat and use a dropper to drop 3-4 drops of urine into the test hole. Wait for about 5 minutes before reading the result. The Check One brand is priced at around 600-800 baht.

Midstream Test: When removing the test kit from the package, remove the cover from the test stick and let the urine pass through the end of the test stick for about 7-10 seconds. Wait for about 5 minutes before reading the result. The Check One brand is priced at around 340-380 baht, while the Clearblue brand is priced at around 1,500-2,000 baht with digital display.

Other methods to help determine ovulation include basal body temperature (BBT) measurement, which should be taken 12-24 hours before ovulation. The body temperature drops and then rises slightly when ovulation occurs due to the hormone progesterone. One must measure their own temperature every morning after sleeping for at least 5 consecutive hours without any activity, such as drinking

water, brushing teeth or going to the bathroom. Record the temperature after measuring it.

The temperature can be measured easily through various methods, such as through the rectum, mouth, or birth canal, depending on the instrument used for the measurement. It is advisable to measure the temperature at a consistent time every day, and if possible, to measure it regularly every 2-3 months to accurately predict ovulation.

For example, from the body temperature graph below, it can be seen that from day 1 to day 13, the body temperature remains low and stable, which is the period before ovulation. On day 14, the ovulation period, the body temperature drops to its lowest point and quickly increases in the next measurement, starting from day 15 onwards. The temperature increase is significant, indicating that ovulation has occurred. On day 29, when the next menstrual cycle is about to begin, the body temperature gradually decreases again.

Observing the cervical mucus or cervical fluid is another way to predict ovulation. The estrogen hormone affects the consistency and elasticity of the cervical mucus, which changes throughout the menstrual cycle. During the period when ovulation is near, the estrogen hormone is at its highest level, causing the cervical mucus to be the most fluid and stretchy. Cervical mucus is divided into 5-6 stages by medical professionals, but for simplicity, it can be divided into 3 stages as follows:

Before ovulation: There is little to no cervical mucus after the end of the menstrual cycle. After a few days, there will be cloudy white or light yellow mucus, but not in large amounts.

Ovulation period: The cervical mucus is abundant, clear and slippery, resembling raw egg whites. It can be stretched to a length of more than 6 centimeters.

After ovulation: The amount of mucus will decrease, become thicker, and less stretchy. If 

you want to check yourself, you can insert your finger into the vagina and observe the mucus that comes out. However, this method can be difficult because the changes in mucus may vary from person to person, and some may not be able to distinguish or observe these changes, especially if there is inflammation in the vagina or if you have had sex, which can make it harder to detect.

The Ferning test is a method that uses a microscope with 50x magnification to examine the shape of cervical mucus in order to determine the time of ovulation. The level of electrolytes in the mucus is believed to correspond to the level of estrogen hormone, which is highest just before ovulation. The level of electrolytes in the mucus causes the mucus to form a fern-like pattern, which allows us to detect the day of ovulation. To perform the Ferning test, you just need to place a drop of mucus on a slide, let it dry, and then examine the fern-like pattern under the microscope. However, this method may be difficult to perform without proper training.

Before ovulation: The mucus appears as small dots or lines.

Near ovulation: The mucus appears to have a slightly fern-like pattern mixed with dots and lines, indicating that ovulation is likely to occur within 3-4 days.

During ovulation: The mucus appears to have a clear fern-like pattern, indicating that ovulation is currently occurring.

We hope that these tips are helpful. If conception still has not occurred after 6-12 months of trying, we recommend that you make an appointment with a fertility specialist to find other causes that may affect your fertility.

We wish everyone who are trying, success.

From Dr. Anchulee Paritworanun

Fertility Center, Vibhavadi Hospital