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How Do Birth Control Pills Actually Work? 3 Doctors Unpack The Pill

Whether you swear by the patch or love your IUD, you may already know what kind of birth control works best for your body. But knowing how birth control actually works is a whole other story.

According to Dr. Sherry Ross, women’s health expert and author of She-ology and She-ology, The She-quel, birth control pills contain different combinations of the hormones estrogen and progesterone. "The pill is meant to mimic your menstrual cycle while preventing ovulation," Dr. Ross tells Elite Daily. "There are many different brands, each varying in the types and doses of these two key hormones. Some people are more sensitive to one or both of these hormones exacerbating these side effects."

According to a 2015 study from the U.S. Department of Health and Human Services, birth control pills or oral contraceptives are among the most popular form of contraceptives used by women and assigned female at birth (AFAB) people. Since there are so many different types of birth control pills, Dr. Ross notes that it's common to try different ones to see what works best for you and your body.

Of course, knowing just what they're doing to your body may help you make an informed decision, so here is how birth control pills actually work.

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They suppress ovulation.

Harkening back to high school health class, pregnancy happens when sperm meets egg — more specifically, the egg needs to be released or discharged from the ovaries (a process known as ovulation).

"You have to ovulate, or release an egg from the ovary, to get pregnant," Dr. Mary Jane Minkin, OB/GYN at Yale-New Haven Hospital and clinical professor at Yale University School of Medicine, tells Elite Daily. "[Birth control pills] suppress ovulation. They keep you from ovulating."

By suppressing ovulation, birth control pills lower the risk of pregnancy. Dr. Alyssa Dweck, MD, also adds that its the combination of estrogen and progesterone that suppresses ovulation. "If an egg isn’t released, pregnancy cannot occur," Dr. Dweck tells Elite Daily.

They let your cervical mucus kill off sperm.

In addition to preventing eggs from being released from your ovaries, birth control pills can ward off sperm. "The progesterone in the pills is quite hostile to sperm," Dr. Minkin says. "It makes the mucus in the cervix hostile to sperm, so sperm trying to come up through the cervix into the uterus are 'killed on contact.'" As Dr. Minkin shares, progesterone hinders sperm from surviving after ejaculation.

Dr. Ross notes that birth control pills kill off sperm by making the cervical mucus thicker, meaning it's difficult for sperm to reach the egg in the first place. "Making the cervical mucus thicker makes it harder for the sperm to swim through to reach the egg," Dr. Ross says.

through it to reach in the egg," Dr. Ross says.

They make your uterine lining thinner.

Birth control pills make your uterine lining thinner and less able to support a fertilized egg. "The pill thins the uterine lining, making it less hospitable for pregnancy," Dr. Dweck says.

ICYMI, the uterine lining, also know as the endometrium, is a layer of cells that lines the inside of the uterus. It's what sheds monthly when you have your period, and is needed during pregnancy to stabilize and support the fertilized egg.

As Dr. Ross shares, during pregnancy, a fertilized egg implants itself into the uterine lining. However, when birth control makes the lining thinner, it's harder for an egg to do so. "[Birth control] makes the uterine lining thin, so it becomes more challenging for a fertilized egg to implant inside the uterus," Dr. Ross says.

Though the pill may be small in size, it's mighty in all that it does for preventing pregnancy. From stopping ovulation to thickening cervical mucus, birth control pills can help you feel in control of your reproductive health.

Experts:

Dr. Sherry Ross, women’s health expert and author of She-ology and She-ology, The She-quel

Dr. Mary Jane Minkin, OB/GYN at at Yale-New Haven Hospital and clinical professor at Yale University School of Medicine

Dr. Alyssa Dweck, MD and New York Magazine's "Top Gynecologist"