Menstruation begins on May 4th. If the menstrual cycle is 28 days, then the 28 days starting from May 4th are the menstrual cycle. The key to calculating ovulation is the menstrual cycle and the length of the menstrual cycle.

If a woman's menstrual cycle is 28 days, her cycle consists of 14 complete cycles and a 14-day fertilization cycle. This means that in the 14 days starting from May 4th to June 9th, a woman’s ovaries may release four eggs.

If any of these four eggs are fertilized, the woman will ovulate around June 13th. At this time, the woman's uterus begins to contract in preparation for the birth of the fetus.

A woman's menstrual cycle and ovulation period can be determined by calculation. Calculations can be made using a calendar or online tool. If you're unsure about your cycle or ovulation, talk to your doctor or professional health care provider.