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How do progestin-only birth control pills work?
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birth control
A 28-day package of birth control pills.
Progestin-only birth control pills, often referred to as minipills or POPs, function through several mechanisms to prevent pregnancy:
- Cervical Mucus Changes: They thicken the mucus in the cervix and make it more acidic, which creates a barrier that makes it difficult for sperm to enter the uterus and reach an egg.123
- Ovulation Suppression: These pills help suppress ovulation, the process by which a mature egg is released from the ovary.14
- Uterine Lining: They thin the lining of the uterus, which further helps in preventing pregnancy.1
Because they do not contain estrogen, minipills are often recommended for individuals who are breastfeeding or those who have health concerns—such as a history of blood clots—that make estrogen-containing contraceptives unsuitable. While highly effective when taken correctly at the same time each day, they are sometimes considered slightly less reliable than combination pills.1423