How does the pill work?
Most birth control pills are “combination pills” containing a combination of the hormones estrogen and progesterone to prevent ovulation (the release of an egg during the monthly cycle). A female cannot get pregnant if she doesn’t ovulate because there is no egg to be fertilized. The Pill also works by thickening the mucus around the cervix, which makes it difficult for sperm to enter the uterus and reach any eggs that may have been released. The hormones in the Pill can also sometimes affect the lining of the uterus, making it difficult for an egg to attach to the wall of the uterus.
Normally, a woman becomes pregnant when an egg released from her ovary (the organ that holds her eggs) is fertilized by a man’s sperm. The fertilized egg attaches to the woman’s womb (uterus), where it receives nourishment and develops into a fetus. Hormones in a woman’s body control the release of the egg from the ovary and prepare the body to accept a fertilized egg. The Pill contains a small amount of synthetic hormones. These hormones work with the body’s natural hormones to prevent pregnancy. Some forms of the Pill stop the body from releasing an egg from the ovary. Others work by making the lining of the womb too thick or too thin to accept the fertilized egg.
