About one-third of pregnancies in the U.S. are unintended, meaning the pregnancy was not planned. This might occur when:
- A couple is open to pregnancy but not specifically trying to get pregnant.
- A couple has sex without contraception.
- A couple has sex with contraception, but the contraception fails or is not used exactly as instructed. Contraceptives are not 100% effective.
When women have unprotected sex or have protected sex but worry the contraception didn’t work, they can turn to emergency contraception (EC).
EC can safely decrease the risk of an unintended pregnancy in these situations.
How does emergency contraception work?
Emergency contraception disrupts ovulation and fertilization. Ovulation is the release of the egg from the ovary. Fertilization occurs when the egg and sperm meet and then join to become an embryo.
Emergency contraception does not interrupt or end a pregnancy. If the egg has been fertilized or has become attached to the uterus, called implantation, EC will not work. Thus, EC is not considered a termination of pregnancy and should be used as soon as possible after unprotected intercourse.
What types of emergency contraception are available?
A common emergency contraception medication is called the “morning-after pill.” This pill contains the drug levonorgestrel and is sold in the United States under the brand names Plan B One-Step, Aftera and others. This progestin-only medication has been approved to sell over the counter since 2006 for women 18 years and older. These pills are widely available at retail pharmacies without a prescription.
For levonorgestrel to work, it is taken ideally within 72 hours of unprotected intercourse. Taking it after the 72-hour time window may reduce its ability to prevent pregnancy.
Another morning-after pill is ulipristal (Ella, Logilia). Ulipristal works by interfering with progesterone, but it is not otherwise a hormone by itself. Ulipristal will stop the ovary from releasing an egg and decrease the thickness of the uterine lining. This emergency contraception is taken as a single dose up to five days after unprotected intercourse, but it requires a prescription.
Intrauterine devices (IUDs) are another option for emergency contraception. They also provide safe, long-term reversible contraception but require an office visit with a healthcare professional for insertion.
Will emergency contraception work for everyone?
It’s recommended that women with obesity, defined as having a body mass index (BMI) of 30 or above, discuss various emergency contraception options with their healthcare team before taking any levonorgestrel morning after pills. That’s because it may not work well, and an alternative method of emergency contraception may be needed.
Emergency contraception should not be used as regular contraception. After using emergency contraception, discuss long-term contraception with your healthcare team. In addition, consider screening for sexually transmitted infections (STIs) after unprotected sex, as emergency contraception doesn’t protect you from STIs.
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