Methods of preventing pregnancy by changing the levels of female hormones in a woman’s body. Hormonal birth control methods include birth control pills, hormone implants or injections, an intrauterine device impregnated with hormones, and morning-after pills. Hormonal birth control methods are easy to use, highly effective, and relatively inexpensive. Hormonal methods work by preventing ovulation. They also cause changes in a woman’s cervical mucus and uterus that help prevent pregnancy. Hormonal birth control methods are relatively safe, but not every woman may be able to use them. Women with certain health conditions, such as high blood pressure or an inherited tendency to develop blood clots, may not be good candidates for using hormonal contraception. Hormonal methods do not protect against sexually transmitted diseases; they should be used in combination with condoms in a non-monogamous relationship.