The contraceptive pill consists of a daily dose of a combination of estrogen and progesterone that is taken orally. It is generally provided to the patient in a pack of 28 pills, one for each day in a typical menstrual cycle, 21 of which contain the active ingredients, the other 7 of which are of no effect and merely allow the patient to remember to take the dose daily. When used properly, the pill is almost totally effective against accidental pregnancy. It's theoretical rate in preventing pregnancy is 99%, but in practice, correct use rarely if ever results in pregnancy.
The pill was developed in the 1960s as an alternative to other contraceptive methods, such as the condom and diaphragm, which were difficult to use and had a higher failure rate.
The pill mimics the hormones that are released during pregnancy, effectively fooling the body into thinking it is pregnant. Through nearly four decades of use, the pill has been shown to be remarkably safe and effective despite early fears that it might lead to cancer or heart disease in later life.
However, the pill has side effects. It is a blood thinner and therefore can complicate surgery. In one episode, a woman who was also on fertility treatments was also using the pill to counteract them, leading to a liver tumor.