What is the exact function of the birth control pill?

Answer 1

Females are born with all the eggs they will have for life. (As opposed to males who don't start producing sperm until puberty and produce it continually thereafter). During puberty, when a girl starts menstruating, she begins to release one egg from one of her ovaries each month. (Sometimes it can be two but more than that is rare). The egg travels through the fallopian tube on the same side as the ovary that released it and down through the uterus where it is flushed out with menstrual blood. If a sperm cell should happen to meet it along the way it could become fertilized. So, anything that prevents the two from coming together will prevent pregnancy. Different methods have different success rates depending on how efficient they are in preventing fertilization. To answer your specific question, contraceptive pills prevent the ovaries from releasing any eggs at all. (Well, over 99% of the time, anyway). Since no egg is released there is nothing for the sperm to fertilize.

Answer 2

There are many uses for Birth Control pills. The most obvious one is to prevent pregnancy, but it can also be used to regulate periods and hormone levels within the body.