Birth control pills are oral contraceptives containing hormones that prevent pregnancy mainly by stopping ovulation. They come in two types: combination pills containing both estrogen and progestin, and progestin-only pills (also called mini-pills). They work by preventing the ovaries from releasing eggs, thickening cervical mucus to block sperm, and sometimes altering the uterine lining to prevent implantation.
Types of Birth Control Pills
- Combination pills : Contain estrogen and progestin. They prevent ovulation, thicken cervical mucus, and change the uterine lining. They usually come in packs with active hormone pills and inactive pills to allow monthly bleeding.
- Progestin-only pills (Mini-pills) : Contain only progestin. Suitable for breastfeeding women or those who cannot take estrogen. They mainly thicken cervical mucus and sometimes prevent ovulation. These have a slightly lower effectiveness than combination pills.
Effectiveness and Use
- When taken correctly every day, birth control pills are about 99% effective at preventing pregnancy.
- Effectiveness decreases if pills are missed or not taken consistently at the same time daily.
- Pills should be taken daily, with some packs having a 21-day or extended cycle regimen.
- Regular medical check-ups, including blood pressure monitoring, are recommended for users.
Side Effects and Risks
- Common side effects include changes in menstrual cycles, nausea, mood changes, breast tenderness, and weight gain.
- Rare but serious risks include blood clots, heart attack, high blood pressure, and stroke, especially in women who smoke or have certain health conditions.
- Progestin-only pills generally have fewer risks than combination pills.
Additional Information
- Emergency contraception such as Plan B contains higher doses of hormones and is used after unprotected sex to prevent pregnancy, working differently than daily birth control pills.
- Newer birth control options may contain different hormone formulations designed to minimize side effects.
In summary, birth control pills are a highly effective, hormone-based method of preventing pregnancy that work primarily by inhibiting ovulation and altering cervical mucus and the uterine lining. They require daily intake and medical supervision for best effectiveness and safety.
