The chances of pregnancy are very low with intercourse on the 3rd day after a clean period, when normally most women don’t ovulate, and a 5%-10% chance of pregnancy will exist. But if the menstrual cycle is very irregular, ovulation will also exist irregular. This is when there is a chance of ovulation wandering, so there is a chance of conception, and emergency contraception should be taken orally to prevent pregnancy. For example, there is also a part of the women, it is ovulation is in the period after the clean 3-5 days or so, this time intercourse will also have the chance of pregnancy. If you don’t want to get pregnant, you should take emergency contraceptive pills to prevent pregnancy. In the future, if you do not want to have children, you should use condoms at all times to avoid abnormal ovulation due to environment, stress and mental factors.