| No, there is no evidence that emergency contraception (EC) increases the risk of ectopic pregnancy — pregnancy outside of the uterus. One study of only 201 women in the U.K. suggested this possibility, but subsequent studies of thousands of women worldwide demonstrate no increased risk.
EC works by stopping ovulation or fertilization. In theory, it could interfere with the implantation of a fertilized egg, but there is no scientific proof that this happens. EC, however, does not affect an established pregnancy. So if EC fails to prevent a pregnancy or a woman who uses EC is already pregnant, her pregnancy — ectopic or uterine — will continue to develop. That’s why women who do not have a normal period following the use of EC should take a pregnancy test and follow up with their clinicians.
Ectopic pregnancy is more likely for women who have had a previous ectopic pregnancy, for women who have had surgery involving the fallopian tubes, and for women who have had sexually transmitted infections. Left untreated with medication or surgery, ectopic pregnancy is a very dangerous, life threatening condition. | 
