How do hormonal methods of birth control primarily prevent pregnancy?

Hormonal methods of birth control primarily prevent pregnancy by inhibiting ovulation, which means they keep the ovaries from releasing eggs. By maintaining a consistent level of hormones, these methods modify the hormonal signals that trigger the ovulatory process. Without the release of an egg, fertilization cannot occur, substantially reducing the likelihood of pregnancy.

While other functions, such as increasing the thickness of cervical mucus, also contribute to the overall effectiveness of hormonal contraceptives, the primary mechanism at play is the suppression of ovulation. This is a critical factor as it directly prevents the egg from being available for sperm to fertilize.