most birth control pills contain a combination of two types of hormones: an estrogen and a progestin. these work together to stop your body's production of a hormone that tells your ovaries to release an egg. so in fact they primarily work by stopping ovulation from occurring each cycle. if there is no egg released there is no egg to fertilize and you prevent pregnancy. the hormones in the birth control pills cause other changes that help to prevent pregnancy as well. nevertheless this is their main mechanism of action.
how do birth control pills work? do they prevent fertilization of the egg or prevent it from attaching to the uterus?