Menstrual disorder refers to a woman's abnormal menstrual cycle, which makes it impossible to accurately predict a woman's menstrual cycle and ovulation period. For women with irregular menstruation, it is very important to calculate the accurate ovulation period because it can help them carry out effective fertility planning.

1. Basal body temperature method: Measuring basal body temperature can help women accurately predict ovulation. Take your oral temperature every morning when you wake up and record it. If the body temperature suddenly rises by 0.3-0.5 degrees Celsius, it may mean that a woman's menstrual cycle is about to end and she is entering the ovulation period.

2. Calendar method: Women can record their menstrual cycles and ovulation periods, and plan their fertility according to the schedule on the calendar. This method requires women to understand their menstrual cycle and ovulation period, and follow the schedule on the calendar to plan their fertility.

3. Body temperature measurement method: Women can measure oral body temperature every day and record changes in body temperature. If the body temperature continues to rise in the first half of the menstrual cycle and gradually drops in the second half of the menstrual cycle, it may mean that the woman's menstrual cycle is about to end and she is entering the ovulation period.