Are oral emergency contraceptives a safe and effective form of long-term birth control?

Yes, but not as effective as some other methods. Annual pregnancy rates in women using pericoital levonorgestrel 150 mcg to 1 mg range from 4.9% to 8.9%; menstrual irregularity is the most common adverse effect (strength of recommendation [SOR]: B, Cochrane review of lower-quality trials). In women younger than 35 years who have sexual intercourse 6 or fewer times per month, correct and consistent use of pericoital levonorgestrel 1.5 mg results in an annual pregnancy rate of 11% (SOR: B, one large prospective, open-label trial). Pericoital contraception is less effective than long-acting reversible contraceptives (annual pregnancy rates of 0.05%-0.8%) or perfect use of combined oral contraceptives (0.3% annual pregnancy rate), but similar to, or better than, typical use of combined oral contraception (9%) and condoms (18%).