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IUDs and Emergency Contraceptives: How Do They Actually Work?

By HERWriter
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how do emergency contraceptives and IUDs actually work? Auremar/PhotoSpin

Do Plan B and my IUD cause abortion? That is the big question these days.

There are various types of birth control, but the owners of the companies Hobby Lobby and an affiliated business Mardel specifically targeted four types of contraceptives in the case they brought to the Supreme Court, Burwell v. Hobby Lobby Stores, Inc.

They have stated that according to their Christian beliefs, four types of contraceptives lead to abortion.

In the actual Supreme Court decision, it describes “four FDA-approved contraceptives that may operate after the fertilization of an egg,” including two types of emergency contraceptives known as “morning after” pills and two forms of intrauterine devices.

“These four methods are not abortifacients,” said Sally Rafie, a pharmacist who provides training on emergency contraception. “The distinction between preventing pregnancy before it begins (contraception) and terminating an existing pregnancy (abortion) is very important.”

“A pregnancy begins [when] the fertilized egg is implanted in the endometrial lining of the uterus, as defined by medical professionals,” she added in an email.

So why did the Supreme Court rule in favor of Hobby Lobby when their main justification was that they believe these four methods of birth control are abortion?

“The Hobby Lobby family has a different religious-based definition that considers a pregnancy when the egg is fertilized by sperm,” Rafie said.

So in this case, the owners of Hobby Lobby and Mardel believe life begins at conception, so in a sense they believe that a woman is pregnant if her egg is fertilized, even if it never implants in the uterus.

So how do these birth control methods actually work?

It is important to note that according to the Office on Women’s Health, emergency contraception will not work if you’re already pregnant.

“While it is possible that [emergency contraceptive pills or ECPs] might work by keeping a fertilized egg from attaching to the uterus, the most up-to-date research suggests that ECPs do not work in this way,” according to their website.

Even some regular birth control pills can be taken at a higher dose in order to act as emergency contraception, according to the website. It is best to use emergency contraceptives ASAP because you are more likely to get pregnant the longer you wait. After five days of unprotected sex, emergency contraceptives are no longer effective.

The two types of emergency contraception listed on the U.S. Food and Drug Administration (FDA) website include levonorgestrel and ulipristal acetate.

1) Levonorgestrel (Plan B, Plan B One-Step and Next Choice)

According to the FDA, this type of contraceptive is used to prevent pregnancy. The main way this pill works is to stop the release of an egg from the ovary. It can also prevent fertilization of the egg and in some cases prevent implantation of the fertilized egg to the uterus.

2) Ulipristal acetate (Ella)

The FDA states that this type of contraceptive is used to prevent pregnancy. The main way this pill works is to delay or stop the release of an egg from the ovary. It can also change the uterine lining in a way that could prevent implantation.

The two types of intrauterine devices (IUDs) include the copper IUD and the IUD with progestin, according to the FDA.

1) Copper IUD (Paragard)

This implanted device can actually last in the uterus for up to 10 years, according to the FDA, and in only some situations it is used as an emergency contraceptive. It doesn’t prevent an ovary from making an egg each month.

However, it prevents sperm from even reaching the egg, it prevents fertilization and in some cases it can prevent implantation of the egg in the uterus.

2. IUD with progestin levonorgestrel (Mirena and Skyla)

This implanted device can last in the uterus for three to five years depending on the type, according to the FDA. It cannot be used as an emergency contraceptive. It can thicken the cervical mucus, which leads to difficulties for sperm trying to reach an egg. It also thins the uterine lining.

According to the Mirena website, it prevents sperm from fertilizing an egg, and in some cases it can prevent the release of an egg from the ovary.

Rafie added that although 16 other birth control methods will be covered by Hobby Lobby after the ruling, the decision will leave some women with no options after unprotected intercourse, which includes cases of rape (unless they can pay out of pocket).

Also, IUDs are a highly effective form of birth control and last longer than all other forms of birth control, even though they have a high up-front cost.

“It is important to note that the levonorgestrel-releasing IUD in particular can be used for medical conditions and not just for preventing pregnancy,” Rafie added. “The levonorgestrel-releasing IUD is FDA-approved for heavy menstrual bleeding, a medical condition that can keep women away from work and other responsibilities.”


Burwell v. Hobby Lobby Stores, Inc. (2014). Pages 18 and 19.

Womenshealth.gov. What is emergency contraception? What are the types of emergency contraception and how do they work? Web. July 2, 2014.

Centers for Disease Control and Prevention. Reversible Methods of Birth Control. Web. July 2, 2014.

Princeton University. Office of Population Research. Association of Reproductive Health Professionals. What is Emergency Contraception? Web. July 2, 2014.

U.S. Food and Drug Administration. Birth Control: Medicines To Help You. Web. July 3, 2014.

Mirena. How Does Mirena Work? Web. July 3, 2014.

Rafie, Sally. Email interview. July 2, 2014.

Reviewed July 4, 2014
by Michele Blacksberg RN
Edited by Jody Smith

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EmpowHER Guest

Levonorgestrel does not prevent implantation of a fertilized egg. It mainly works to prevent ovulation and may also thicken cervical mucus to keep sperm from reaching an egg.

July 7, 2014 - 7:11am
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