What is it?

This medication goes by many names: the morning-after pill, Plan B, backup birth control, emergency contraception, and more. These names all refer to a group of medications which have been used by nearly a quarter — 24.3 percent — of sexually active women in the U.S., according to the Centers for Disease Control and Prevention.

These pills can be used for many reasons, such as after having unprotected or unplanned sex, or when other methods of contraception have failed, like a broken condom or a missed birth control pill.

One popular type of emergency contraception is a pill called levonorgestrel. There are many brands of levonorgestrel, including Plan B-One Step, Next Step, Take Action, and more. Levonorgestrel can be used up to 72 hours or three days after intercourse. This is typically the most accessible option because it can be obtained without a prescription at most drugstores. Health centers such as Planned Parenthood also commonly carry levonorgestrel.

Ulipristal, often known by the brand name ella, is another option available. However, unlike levonorgestrel, this medication requires a prescription. Ulipristal is more effective than levonorgestrel, and it can be taken up to 120 hours or five days after intercourse.

Both medications are very effective when used as directed. Studies have shown that only 1.8 percent of people become pregnant after using ulipristal for emergency contraception, and only 2.6 percent with levonorgestrel. Both medications are more effective the sooner they are taken. Notably, levonorgestrel is less effective in people who weigh more than 165 pounds. So, if possible, these individuals should try to see a doctor to discuss other methods of emergency contraception, such as ulipristal or the copper IUD.

How do these medications work?

The mechanism of emergency contraceptive pills has been well studied since Plan B was first approved by the Food and Drug Administration in 1997. Both levonorgestrel and ulipristal work by interrupting the process of ovulation, which occurs when the ovary releases an egg. Normally, the egg would then go into the lower fallopian tube and uterus, where it can be fertilized if sperm are present. Pregnancy occurs when a fertilized egg implants into the endometrium, the lining of the uterus.

Levonorgestrel interrupts ovulation by preventing the brain from releasing luteinizing hormone. When LH is released, the ovary detects it and becomes triggered to release an egg. Ulipristal works similarly by preventing the ovary from detecting LH. In both cases, the ovary does not release an egg, thus preventing fertilization of the egg from occurring. This is similar to how regular oral contraceptives — “the pill” — prevent pregnancy.

How does it not work?

Emergency contraception does not work by preventing sperm from fertilizing an egg. It also does not prevent implantation of an egg that has already been fertilized. Emergency contraception does not terminate an existing pregnancy or cause an abortion. Additionally, there is no evidence to suggest that using emergency contraception will negatively impact future fertility.

What does it mean?

Though the topic of emergency contraception can be an embarrassing one for many, it is important to understand options for preventing pregnancy. If you think you may be pregnant and it has been at least 10 days since you’ve had unprotected sex, you should consider taking a pregnancy test. Individuals in Iowa City can contact their primary care provider, UI Student Health, Planned Parenthood, or the Emma Goldman Clinic for more information about options available to them to prevent or detect pregnancy.

• Emily Ruba, Fourth year medical student at the Carver College of Medicine