This largely accounts for the gap in OC effectiveness between perfect users and typical users. Irregular pill-taking may explain why users of oral contraceptives sometimes experience higher pregnancy rates than users of injectables, IUDs, or implants. Long-term effectiveness of the pill requires sustained correct and consistent use. Preventing ectopic pregnancy. Protection against ectopic pregnancy is a benefit of all contraceptive methods, to varying degrees.
Ectopic pregnancy is fairly common.
In the US ectopic pregnancy is the leading cause of pregnancy-related death in the first trimester.