Ovulation is an important period of pregnancy, usually starting on the 14th day of the menstrual cycle and ending on the 16th day. For couples trying to have a baby, it's important to know when ovulation occurs.

So, how to determine your ovulation period? This can be determined by:

1. Measure body temperature: Measure basal body temperature every day and record it on the thermometer. Starting on the 14th day of the menstrual cycle, body temperature will begin to rise and peak on the 16th day.

2. Observe the cervix: Starting on the 14th day of the menstrual cycle, observe whether the cervix begins to open. If your cervix starts to open, it means you may be having a cycle.

3. Measure blood HCG: Beginning on the 14th day of the menstrual cycle, measure blood HCG levels. This is an important indicator of pregnancy.

4. Use David test strips: David test strips can start testing on the 14th day of the menstrual cycle. Test results are usually given within 2-3 days.

The above methods are just some references and are not absolute. If you have any concerns, it is best to consult a doctor or professional advisor.

For couples trying to have a baby, it's important to know when ovulation occurs. Having sex during ovulation can increase your chances of getting pregnant. However, if you don't have any plans to get pregnant, don't worry too much, there are still many other ways to stay healthy and happy.