Methods for Calculating Your Ovulation Period

How is the ovulation period calculated?

There are several methods for calculating ovulation:

• Calendar Method
• Basal Body Temperature Method
• Cervical Mucus Method (Ovulation Method)
• Cervical Position Method (Manual Self-Examination of the Cervix)

Calendar Method

To determine when she is most fertile, a woman needs to record the details of her menstrual cycle on a calendar for 8 to 12 months. To do this, the first day of each period should be marked on the calendar as day 1. The length of the menstrual cycle may vary from month to month; how many days each cycle lasts should also be written down.

To calculate the day of ovulation, 18 is subtracted from the number of days in the shortest cycle recorded on the calendar. The result is added to the first day of the next period. The resulting day is noted. This day marks the first day on which the woman is fertile. For the last day, 11 days are subtracted from the number of days in the longest cycle.

Suppose a woman's first day of menstruation is January 25, 2021, and her cycle lasts 27 days;

27-18 gives 9. This result is added to the next period date, February 20, 2021. Result: since February has 28 days, it falls on March 1, 2021. Accordingly, the first day on which this person has a high chance of ovulating will be March 1, 2021 (the ovulation period will occur between March 1 and March 7, 2021).

Basal body temperature method

A person's body temperature in the morning before moving around is called basal body temperature. This temperature can rise with ovulation. Ovulation days can be estimated by recording basal body temperature daily for several months. Basal body temperature can vary from woman to woman. Progesterone, which is secreted after ovulation, raises body temperature by 0.2°C to 0.5°C and keeps it elevated until the next period; this rise is called the thermal shift. Measuring it forms the basis of the basal body temperature method.

A sudden rise in body temperature may not always coincide with ovulation, but in almost everyone ovulation occurs within three days after this rise in temperature. The likelihood of becoming pregnant is highest from 2 to 3 days before body temperature reaches its peak until 12 to 24 hours after ovulation.

There are basal body thermometers specially made to be sensitive for measuring basal body temperature.

There are basal body thermometers specially made to be sensitive for measuring basal body temperature.

Cervical mucus method

This method involves tracking changes in cervical mucus, that is, the discharge from the cervix, during the ovulation period. Hormones can cause changes in the mucus before and during ovulation. It is necessary and important to record the changes in the mucus on a calendar; depending on its consistency, it can be noted as "sticky", "dry" or "slippery".

Right after the period, there are “dry days” when there is no mucus. However, as ovulation approaches and the egg begins to mature, the amount of mucus in the vagina increases and becomes visible at the vaginal opening. This mucus is white or yellowish, cloudy and sticky. Just before ovulation, the amount of mucus reaches its highest level. On these days the mucus is clear and slippery. This is when the person is most fertile. About four days after the start of the fertile period, the consistency of the mucus changes again. The amount of mucus decreases rapidly, and it becomes sticky and cloudy again. Before the next period, a dry phase may begin again.

Cervical position method

The secretion of cervical mucus also causes various physical changes in the cervix. It is possible for a woman to identify these changes in the cervix by examining herself manually. During the infertile phase, the external opening of the cervix is closed, it is firmer and it can be reached easily by hand. As ovulation approaches and estrogen rises accordingly, the cervix softens, moves higher and its external opening opens. This softening becomes noticeable about 3-4 days before ovulation on average. This phase means that fertility is increasing. When this phase ends, the cervix becomes firmer again.

How do women with irregular periods calculate their ovulation period?

Every woman of reproductive age has a menstrual period about once every 28 days on average.

Menstrual irregularity:

• Bleeding at intervals of less than 21 days or more than 35 days
• No periods for 3 or more cycles,
• Periods that are shorter or longer than normal

These are considered menstrual irregularities.

These conditions are mostly caused by hormonal imbalances. They can also be associated with growths such as ovarian cysts, fibroids and polyps, as well as with diseases such as diabetes and depression.

Women with irregular periods will not be able to calculate their ovulation period using period-tracking methods. In this case, they can try to determine their ovulation period with the help of ovulation kits sold in pharmacies. However, the causes of the menstrual irregularity should be investigated, and an obstetrician-gynecologist must be consulted for its treatment.