Hormonal contraception does its job by introducing synthetic hormones, like progestin, estrogen, or a mix of both, into your body.
These hormones send signals to your reproductive system to prevent ovulation, so no egg gets released for fertilization. They also thicken cervical mucus to make it harder for sperm to swim up and meet an egg, and sometimes they can even thin the lining of your uterus, making it less likely for a fertilized egg to implant, preventing pregnancy.