Emergency contraception may be used to prevent pregnancy for a short period of time after unprotected sex. Commonly used emergency contraception methods include
copper IUD, probably requires insertion within 5 days of unprotected intercourse
For women who have regular menses, the risk of pregnancy after a single act of intercourse is approximately 5%. This risk is 20 to 30% if intercourse occurs at midcycle.
When an or is used for emergency contraception, it must be inserted within 5 days of unprotected intercourse (or within 5 days of suspected ovulation, if the timing of ovulation can be estimated). The pregnancy rate with is 0.1% for emergency contraception with the copper-releasing IUD and 0.3% for the 52-mg levonorgestrel-releasing IUD (1). Also, the IUD can be left in place to be used for long-term contraception. As emergency contraception, the copper IUD may affect blastocyst implantation; however, it does not appear to disrupt an already established pregnancy. The resumption of menses plus a negative pregnancy test reliably excludes pregnancy; a pregnancy test should be done 2 to 3 weeks after insertion to be sure that an unintended pregnancy has not occurred before insertion.
(1.5 mg, single dose) used as emergency contraception prevents pregnancy by inhibiting or delaying ovulation. The probability of pregnancy is reduced by 85% after oral levonorgestrel emergency contraception, which has a pregnancy rate of 2 to 3%. However, overall risk reduction depends on the following:
The woman's risk of pregnancy without emergency contraception
The time in the menstrual cycle that emergency contraception is given
The woman's body mass index (BMI; levonorgestrel
In the United States, oral levonorgestrel emergency contraception is available behind pharmacy counters without a prescription. A hormonal contraceptive may be started at the same time as use of oral levonorgestrel as part of a quick-start protocol. A backup method (such as a condom) is recommended for 7 days.
(a single oral dose of 30 mg), a progestincopperprogestins may interfere with emergency contraceptive efficacy. If hormonal contraception is started on day 6, a backup method (such as a condom) should be used for 7 days.
levonorgestrel and ulipristal emergency contraception should be taken as soon as possible and within 120 hours of unprotected intercourse.
The Yuzpe methodestrogen dose often causes nausea and may cause vomiting. A hormonal contraceptive may be started at the same time as use of the Yuzpe method, as part of a quick-start protocol. A backup method (such as a condom) is recommended for 7 days. The Yuzpe method is less effective than other methods; thus, it is no longer recommended except when women do not have access to other methods.
A urine pregnancy test 2 weeks after use of emergency contraception is recommended.
General reference
1. Turok DK, Gero A, Simmons RG, et al: Levonorgestrel vs. copper intrauterine devices for emergency contraception. N Engl J Med 384 (4):335–344, 2021. doi: 10.1056/NEJMoa2022141
Key Points
Likelihood of pregnancy after hormonal emergency contraception depends on pregnancy risk without emergency contraception, time in the menstrual cycle that emergency contraception is taken, and BMI.
