If the menstruation is regular, the chance of pregnancy during the safety period is almost zero; if the menstruation is irregular, you can not accurately calculate the safety period, there is a possibility of pregnancy, it is best to calculate the safety period according to your own situation. If your period is irregular, it is recommended to take good contraceptive measures, you can use condoms; if your period is regular and you have intercourse during the safe period and there is a delay in your period, this may be an irregular period, not necessarily pregnancy, you can rule out early pregnancy test if you are not sure. If the irregular menstruation, may be caused by taking medicine, staying up late, mental tension, etc., the best reasonable regulation, at the same time, it is recommended to pay attention to strengthen the diet and nutrition, it is best not to eat spicy and stimulating food, do not overwork, it is recommended to exercise properly, can be improved.