In women who have regular periods, the risk of pregnancy after a single intercourse is about 5%. This risk is 20 to 30% if intercourse occurs in the middle of the cycle. Checking with a pregnancy test 2 weeks after using emergency contraception is recommended. Commonly used methods of emergency contraception include: Insertion of a copper IUD within 5 days of unprotected intercourse. Insertion of a release IUD containing 52 mg of levonorgestrel, which, like the copper-bearing IUD, requires insertion within 5 days of unprotected intercourse. Taking 1.5 mg of levonorgestrel orally once within 120 hours after unprotected intercourse. Taking 30 mg of ulipristal acetate orally once within 120 hours after unprotected intercourse. When a copper-containing or levonorgestrel-releasing IUD is used for emergency contraception, it should be inserted within 5 days of unprotected intercourse (or within 5 days of suspected ovulation if the time of ovulation can be estimated). The pregnancy rate was about 0.1% for emergency contraception with copper-releasing IUDs and 0.3% for levonorgestrel. Also, the IUD can be left in place to be used for long-term contraception. As emergency contraception, the copper-containing intrauterine device may affect the implantation of the blastocyst, but does not disrupt an already established pregnancy. Resumption of menstruation plus a negative pregnancy test reliably rules out pregnancy. A pregnancy test should be done 2 to 3 weeks after insertion to ensure that no unwanted pregnancy occurred prior to insertion. A single dose of oral levonorgestrel used as emergency contraception prevents pregnancy by inhibiting or delaying ovulation. The chance of pregnancy is reduced by 85% after oral emergency contraception with levonorgestrel, which has a pregnancy rate of 2 to 3%. However, the overall risk reduction depends on: The time in the menstrual cycle that emergency contraception is given. Body mass index of a woman. Emergency contraception with levonorgestrel is less effective than ulipristal acetate in obese women. Ulipristal acetate is a progestin receptor modulator and has a pregnancy rate of about 1.5%. It is more effective than oral levonorgestrel. Ulipristal acetate, like levonorgestrel, prevents pregnancy mainly by delaying or inhibiting ovulation. Although ulipristal acetate is more effective than levonorgestrel, its effectiveness also decreases with increasing body mass index. Thus, in obese women who strongly desire to avoid an unwanted pregnancy, the copper IUD is the preferred method of emergency contraception. Hormonal oral contraception should not be started until 6 days after using ulipristal acetate,as progestins may affect the efficacy of emergency contraception. There are no absolute contraindications for emergency contraception with levonorgestrel or ulipristal acetate. They should be administered as soon as possible and within 120 hours of unprotected intercourse. Taking pills for emergency contraception leads to the appearance of some side effects, which are usually short-lived. Adverse drug reactions may include: abdominal pain, chest pain, dizziness, fatigue, headache and nausea. Very often, taking this type of medication has an effect on the next menstruation /injury or delay of the cycle, or scanty spotting/. Bibliography: https://www.msdmanuals.com/en-sg/professional/gynecology-and-obstetrics/family-planning/emergency-contraception https://my.clevelandclinic.org/health/drugs/15653-emergency-contraception