How Birth Control Pills Work

Birth control pills prevent pregnancy primarily by suppressing ovulation, thickening cervical fluid, and altering the uterine lining. Here is a more detailed explanation of how they work:

1. Ovulation Suppression:

- Combination pills: These contain two types of hormones, estrogen and progestin, which work together to prevent the ovaries from releasing eggs (ovulation). Estrogen halts the growth and release of an egg from the ovaries, while progestin stops the ovary from fully maturing.

- Progestin-only pills: These pills contain progestin only and also work by preventing ovulation.

2. Thickening of Cervical Fluid:

- Progestin in birth control pills causes the mucus in the cervix to become thicker and stickier, which makes it more challenging for sperm to reach and fertilize an egg.

3. Changes to the Uterine Lining:

- The progestin in birth control pills affects the lining of the uterus (endometrium), thinning it and making it less hospitable for the implantation of a fertilized egg.

4. Additional Mechanisms:

- Besides these primary effects, birth control pills may also interfere with sperm transport and the fertilization process if ovulation occurs despite their use.

It is important to remember that birth control pills must be taken consistently as directed by a doctor or healthcare provider for effective pregnancy prevention. Missing pills or not using them correctly can compromise their efficacy. Additional contraceptive methods, such as condoms, may be recommended during times of missed pills or medication interactions to ensure reliable contraception.