There are lots of different types of “pills” related to pregnancy. It’s most helpful to break them into two categories:
1: Contraceptives PREVENT someone from becoming pregnant.
2: Different types of pills are used when there is ALREADY an established pregnancy. It’s mifepristone, from this second group, whose FDA approval is currently being contested in the U.S. court system.
For all you nerds out there, here’s the detailed explanation of pill types and how they work:
Group 1: Contraceptives (“Contra” – against, “ception” – conception) are used to prevent pregnancy from happening in the first place. These include both typical birth control pills and emergency contraceptives. Contraceptives will NOT end an already established pregnancy. All of these types of pills are currently legal in all states in the U.S.
The original oral contraceptive, “The Pill”, is available under many different names. These are classified as Combined Hormonal Contraceptives (CHCs), because they contain both an estrogen and a progestin. This combination of medications works in multiple ways- it thickens the cervical mucus to block sperm, thins the uterine lining, and prevents the ovaries from releasing an egg. CHCs work to prevent fertilization, or a sperm and egg from coming together. Without fertilization, pregnancy cannot occur.
Pills with just progestins are also available. These estrogen-free pills are safer for people with some specific medical conditions such as a history of blood clots or specific types of migraine headaches. The “Mini-Pill” was the first type developed and uses a very low dose of progestin. A different type of progestin-only pill was also recently introduced, marketed in the U.S. as “Slynd”. These both work to prevent fertilization and implantation.
Emergency contraceptives (EC) are pills that also work to prevent pregnancy from occurring. Unlike the pills above that are taken daily, ECs are taken after intercourse has already occurred, which led to the nickname “morning-after pill.” Since sperm are already well on their way, these types of pills work to delay release of an egg from the ovary (ovulation) if it has not already occurred. This delay gives time for many of the sperm to die off, so that hopefully by the time the egg is released, it is less likely that sperm will still be present to fertilize it.
There are two main categories of EC. The over-the-counter forms called Plan B One Step, Take Action, My Way, Option 2, Preventeza, AfterPill, My Choice, Aftera, and EContra (active ingredient levonorgestrel, most effective for people who weigh less than 165 lbs and/or who have had sex within the last 3 days) and the prescription form of EC, called ella® (active ingredient ulipristal, most effective for people who weigh less than 195 lbs and/or have had sex within the last 5 days).
** Note: Although this post is about all the ”pills” related to pregnancy, it is important to note that there is also a non-pill form of emergency contraception (EC), called the IUD. This is a more effective form of EC for people who weigh more than 165 lbs (for Plan B and generics) and more than 195 lbs (for ella®). Since IUDs and ella® do require a visit to a clinician, if you weigh more than 165lbs, talk to your clinician now about which form of emergency contraception is best for you. Read more about IUDs as EC here.
There has been some concern voiced about the possibility of these medications preventing implantation of a fertilized egg in the uterine lining, but this has not been shown to be common and is not the way these meds prevent pregnancy.
Group 2: This category of pills is used AFTER someone is already pregnant or potentially pregnant There are two medications in this category: misoprostol and mifepristone.
Misoprostol works to open the cervix and encourage the uterus to contract. It has many uses including labor induction in pregnancy, treatment of miscarriage, and even to make non-pregnancy related gynecologic procedures more comfortable and effective. Misoprostol has also long been used as a medication to cause an abortion, especially early in a pregnancy. Interestingly, misoprostol was originally brought to market for treatment of stomach ulcers and is sometimes used in treatment of GI disorders.
Mifepristone is the other medication in this category. It causes breakdown of the lining of the uterus and sensitizes or “primes” the uterine muscle for contraction. Using it together with misoprostol has improved the safety and effectiveness of both miscarriage treatment and medical abortions. Medical organizations currently recommend that they be used together for both situations.
Misoprostol and mifepristone taken together are also used as what is sometimes called “missed period pills,” in which a person who is late for their period (and potentially pregnant) takes them to “bring on” a period without first checking a pregnancy test. The legality of this approach in states that ban abortion is unclear.
Mifepristone is the drug whose availability in the U.S. has recently been called into question by a court case challenging the FDA’s approval of the drug. As the case makes its way through the Federal Appeals Court and, likely, the Supreme Court, mifepristone may become unavailable in the U.S. (even in those states where abortion is still legal). This would restrict access to the best standard of care for both early abortion and for miscarriages. Misoprostol alone can still be used, but it is slightly less effective than the combination with mifepristone. We have also started to see much stricter regulation of misoprostol itself which impacts much more than abortion given the many uses of this medication.
Mifepristone was first approved by the FDA in 2000 as a safe way to end a pregnancy up to 10 weeks. The first generic version of mifepristone was approved by the FDA in 2019, and another generic version was just approved in October, 2025. Generic versions of medications have the same strength and effect in the body, but allow it to be offered at a much lower cost.
In November 2022, the Alliance for Hippocratic Medicine filed a lawsuit against the Federal Drug Administration (FDA) to challenge the legality of mifepristone. In June 2024, the US Supreme Court ruled that mifepristone is safe and will remain accessible through pharmacies and telemedicine. The Court determined that there was no evidence to stop the use of mifepristone. Medication abortions are legal in states that do not have total abortion bans. Currently, 28 states limit access to medication abortion and 12 states have a total abortion ban.
Bottom line: Contraceptives, including The Pill and Emergency Contraception, work to prevent pregnancy and are not under legal challenge in the U.S. On the other hand, misoprostol and mifepristone are drugs used when someone is ending an existing pregnancy, whether intentionally (abortion) or not (miscarriage). Mifepristone is the one under the most legal challenge but is still currently available in some states in the U.S.
Stay safe, stay well!
Those Nerdy Girls
