Health & Fitness

Emergency Contraceptive Pills: How They Work, Safety and Side Effects

Emergency Contraceptive Pills

Preventing unintended pregnancies is a major public health concern and is very important for an individual who intends to avoid pregnancy or to maintain a time gap between two pregnancies. Emergency contraceptive pills are taken to prevent pregnancy after unprotected sexual intercourse. It comes to rescue when a condom accidentally breaks, women forget to take regular contraceptive pills, or in the event of a sexual assault. They are most effective when taken within 72 hours of intercourse, especially during the first 24 hours.

How do emergency contraceptive pills work?

Emergency contraceptive pills (ECPs) include LNG (levonorgestrel) and ulipristal acetate. LNG is a synthetic progestin and is taken orally as a single dose of 1.5 mg. LNG works by preventing or delaying ovulation. It can also increase the thickness of the cervical mucus, preventing the entry of the sperm through the genital tract, and thus, inhibiting fertilization. Efficacy of LNG is 95% when taken during the first 24 hours after the sexual act.

Ulipristal acetate is a selective progesterone receptor modulator. It is taken as a single dose of 30 mg. Ulipristal acetate is seen to delay or inhibit ovulation. Research shows that it can delay ovulation by 24–48 hours. Another mechanism involves reducing the endometrial thickness and delaying endometrial maturation, which is essential for implantation.

Alternatively, the Yuzpe method can be used, which involves the use of estrogen combined with levonorgestrel. Each dose contains of 100–120 mcg estrogen (ethinylestradiol) and 0.50–0.60 mg levonorgestrel or 1.0–1.2 mg norgestrel (progestin). In this method, the ordinary contraceptive pills are used in certain combinations as emergency contraception. This method works by impeding implantation and delaying ovulation. Depending on the concentration of estrogen/progestin, each dose includes 4–6 pills. Two doses should be taken with an interval of 12 hours. The Yuzpe method is 77% efficient if taken within the first 24 hours of intercourse.

Safety and side effects associated with emergency contraceptive pills

Side effects of ECP:

Side effects associated with ECP are rare and mild. According to the Center for Disease Control’s Medical Eligibility Criteria for Contraceptive Use, there is no circumstance where the risks of using combined or levonorgestrel ECPs outweigh the benefits.

The side effects of LNG contraceptive pills are similar to those of other contraceptive pills like headache, nausea, breast tenderness, fluctuation in weight, and spotting. Research shows that LNG is better tolerated as compared to the Yuzpe method. Females who are lactating or have a history of migraines, stroke, liver disease, or cardiovascular disorder should be given LNG contraceptive pills. When LNG is taken during initial days of the menstrual cycle, it  shortens menstrual cycle’s length, but when taken later in the cycle, it may have no effect at all on the length of the cycle.

Ulipristal is well tolerated and side effects are generally self-limiting. Side effects are the same as that of LNG. Side effects of using the Yuzpe method are bloating, headache, and uterine cramps.

Safety of ECP

Emergency contraceptive pills cannot be given to anyone who is pregnant, has a history of stroke, active liver disease, untreated hypertension, or suffers from an estrogen-sensitive tumor.

There is no proved teratogenic (cancer) risk in pregnancies that occur while women are on emergency contraceptive pills. Risk of birth defects in a baby is unlikely. Thus, pregnancies that happen should not be terminated only because emergency contraceptive was used. Moreover, history of ectopic pregnancy is not a contraindication for giving ECP.

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