Ovulation can be delayed or advanced due to emotional changes, restlessness, late nights, stress, or irregular work and rest habits, all of which can cause endocrine changes and thus delay or advance ovulation. However, in general, as long as the menstrual cycle is regular, ovulation often occurs about 14 days before the next menstrual period. So a woman with a 30-day menstrual cycle is not the same as a woman with a 45-day menstrual cycle. Also if you plan to prepare for pregnancy, you can check with ovulation test paper to see the exact time of ovulation and then arrange intercourse, which will increase the chance of conception. But if you use ovulation, safe period contraception, this method is not reliable because there are many clinical cases of this unwanted pregnancy. If it is contraception, it is recommended to take the condom or short-acting contraceptive pill method, which is more reliable, and the method is simple, safe and has few side effects.