There is a small chance of pregnancy when there is sexual contact 4 days before menstruation, because it is not during ovulation. The chances of pregnancy are greater if you have intercourse within the ovulation period, and if you usually have a regular menstrual cycle, you can predict the ovulation period based on the time of your next menstrual period. 14 days after ovulation to the next menstrual period, before and after ovulation within 4-5 days of intercourse, the chances of pregnancy are greater, of course, ovulation will be affected by the environment, emotions, sex, taking contraceptives and other factors occurring in advance or staggered ovulation, and sometimes additional ovulation, but the chances of this happening are relatively small. Sex 4 days before normal menstruation will not result in pregnancy. Except this vaginal bleeding is not normal menstruation, but abnormal vaginal bleeding after pregnancy.