Here’s how to determine your monthly ovulation period:

1. Basal body temperature method: Measuring basal body temperature can understand the changes in the internal temperature of the body. Take your oral or anal temperature every morning when you wake up and record changes in body temperature. Generally speaking, a woman's body temperature will follow a certain pattern every month, and the ovulation period will occur within a few days after the body temperature rises. This method requires daily measurements and recording in order to analyze trends.

2. Calendar method: Record a woman’s menstrual cycle on a calendar and deduce the monthly ovulation period based on the rules. This method requires accurate recording of a woman's menstrual cycle in order to analyze trends.

3. David’s Test Strip: The David’s Test Strip is a test that determines monthly ovulation. Insert the test strip deep into the vagina and wait 2-3 minutes to read the result. Typically, the test strip will show a brightly colored line indicating fertilization and ovulation.

4. Measure blood pressure: Measuring blood pressure can help you understand the supply of oxygen and nutrients inside a woman’s body. Take your blood pressure every morning when you wake up. Generally speaking, women's blood pressure will be regular every month, and the ovulation period will occur within a few days when the blood pressure rises.

The above are several commonly used methods to determine the monthly ovulation period. Of course, these methods are not completely accurate in determining a woman's ovulation period, but they can provide a certain reference. If couples want to have children, it is recommended to observe and infer according to the above methods in order to better grasp the ovulation period. At the same time, it is recommended that couples undergo adequate health examinations to ensure good health before preparing for pregnancy.