Birth control pills work by releasing hormones into a woman's body to alter her regular hormonal balance, causing the processes associated with menstruation to fail, according to TeensHealth. Without proper hormone levels, a woman is unable to prepare for pregnancy and a man's sperm has difficulty reaching the uterus.Continue Reading
Many birth control pills completely prevent the act of ovulation, which means that an egg is never released from the ovaries to be fertilized, even if a man's sperm is somehow able to successfully reach the uterus, explains TeensHealth. If an egg is released, the uterus is likely no longer a hospitable place for the egg to attach due to the hormonal changes caused by oral contraceptives. Most birth control pills come in packs that allow for a seven-day break in hormone consumption, either by providing 28 pills with seven that don't have hormones, or by supplying a 21-day pack that requires a woman to go seven days without taking any pills.
Women have a choice between which type of pack they prefer to take, according to TeensHealth. Some contraceptive pills are designed to be taken for 12 weeks straight with only a single gap of seven days' worth of inactive pills. In this plan, a woman only menstruates once every three months.Learn more about Birth Control