How Does Birth Control Work


Birth control pills use hormones to prevent pregnancy. The tablets in your pack contain synthetic versions of two kinds of naturally-occurring hormones. Combination pills contain both an estrogen and a progestin, while progestin-only pills contain only a progestin.|

These hormones work by preventing the sperm from fertilizing an egg after sex—no contact between sperm and egg = no pregnancy. They also make it harder for a fertilized egg to mature into a pregnancy.

What Types of Birth Control Are There?

There are 2 main classes of oral contraceptives. These classes are based on whether the tablets contain a single hormone called progestin or a mix of estrogen and progestin.

Combination pills contain a mix of 2 hormones that work to stop pregnancy, an estrogen and a progestin.

Progestin-only pills(sometimes called “minipills”) contain only 1 hormone, progestin.

Combination pills are either conventional or extended-cycle. They’re also further divided into monophasic or multiphasic packs. Don’t worry— we’ll cover all the details later on.

To learn more, read out extensive birth control guide:

What's the Difference Between Combination Pills and Progestin-only Pills?


While closely related, the apparent difference between the two types of pills is that a combination pill contains estrogen and a progestin-only pill doesn’t. But this small difference has a definitive impact when it comes to your body.


So how does the pill work inside your body? Again, both types of pills use hormones to prevent pregnancy. The combination pill causes 3 significant changes in your body to do this.



Combination pills

  • prevent the ovaries from releasing an egg

  • thicken cervical mucus

  • thin the uterine lining


These changes make it harder for the sperm to reach the egg and for a fertilized egg to become attached to the uterine lining.

Most progestin-only pills, or minipills, cause only 2 of these changes in your body.


  • thicken cervical mucus

  • thin the uterine lining


Indeed, a small percentage of progestin-only pills can also prevent ovulation (the release of an egg from the ovaries). But for the most part, the minipill won’t cause you to stop ovulating.


What is Low-Dose Birth Control?


Low-dose options are available for combination pills. While closely related to the regular, higher-dose tablets, these meds contain a lower daily dose of hormones.


Low-hormone birth control is just as effective at pregnancy prevention. It’s believed that pills with lower hormonal doses can decrease some of the classic side effects caused by higher-dose pills. These include side effects like headaches, breast tenderness, nausea, and vomiting.


Some of the most common low-dose birth control pills in the combination class are

  • Apri

  • Aviane

  • Levora

  • Levlen-21

  • Ortho-Novum

  • Yasmin

  • Yaz

What is the Best Birth Control Pill?


Since birth control isn’t a one-size-fits-all medication, the right type for one woman may not work for another. That’s why we encourage you to ask this question instead: which birth control is best for me? When looking at your choices, there are some essential factors to take into consideration. These include your health and medical history, age, lifestyle, and your unique needs.


We want to empower you with as much information as possible as you explore your options, but we also encourage you to work with a licensed doctor or nurse practitioner (NP) when choosing a pill. The Lemonaid medical team is always happy to help you understand the birth control landscape. We’ll make sure you find an option that works well for you and is as safe as possible.


Birth control

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