How does the progestin-only pill (mini-pill) primarily prevent pregnancy?

• A. By preventing ovulation
• B. By thickening cervical mucus
• C. By blocking uterine implantation
• D. By regulating menstrual cycles

Answer: (B)

The progestin-only pill, commonly known as the mini-pill, primarily works by thickening cervical mucus. This increased viscosity of the cervical mucus makes it more challenging for sperm to swim through the cervical canal and reach an egg for fertilization. Additionally, the thickened mucus can act as a barrier to prevent sperm from entering the uterus.

While the mini-pill can have some effects on ovulation, its primary mode of action does not rely on consistently preventing ovulation as is the case with combination oral contraceptives. Moreover, the mini-pill does not block uterine implantation directly; instead, it creates an environment that is less favorable for sperm motility and function. Regulating menstrual cycles is another effect of the mini-pill, but it is not the primary mechanism of how it prevents pregnancy. Understanding these mechanisms is crucial for proper contraceptive counseling and for selecting the most suitable method for individual patients.