The main mechanism of action of the emergency contraceptive pill is to inhibit follicular ovulation, change the thickness of the endometrium and prevent the fertilized egg from being laid. After pregnancy, you should pay attention to observe whether there is pain in the stomach and bleeding phenomenon, there is pain in the stomach or bleeding may be the birth control pills may lead to miscarriage, there is no need to keep the fetus can let it be natural; no phenomenon at all, do not be too nervous to keep the fetus, in the middle and late pregnancy in time to do Down’s syndrome screening and four-dimensional examination, no problem means that the fetus is healthy can be kept.