Birth control, also known as contraception, refers to any activity, medication, or device used to prevent pregnancy. Choosing a method of birth control is highly personal. Factors to consider include your health, age, frequency of sexual activity, desire to have children in the future, and family medical history. It's important to consult your doctor when choosing a method, whether or not your choice requires a prescription. Birth control methods vary in effectiveness and work in different ways. They can kill sperm or block it from reaching the egg. Some methods prevent eggs from being released by the ovaries. Others change the cervical mucus to hinder sperm from moving into the uterus, or alter the tissue lining the uterus so that a fertilized egg can't implant. Some contraceptive methods that don't require a prescription include spermicides, male and female condoms, and periodic abstinence (for example, natural family planning), which includes a number of methods designed to help avoid having unprotected sexual intercourse during the most fertile times of a woman's menstrual cycle. Remember, the proper use of condoms will prevent unwanted pregnancy and the spread of sexually-transmitted diseases. Methods that require a visit to your doctor include the following: Oral contraceptives (birth control pills): Medications taken daily that prevent ovulation by controlling pituitary hormone secretion. Usually, oral contraceptives contain the hormones estrogen and progestin. They also help regulate menstrual cycles and decrease the amount and length of menstrual periods. Mini-pill: This daily pill has only one hormone, progestin. It thickens cervical mucus and prevents the sperm from reaching the egg. The mini-pill also can decrease the flow of your period. Depo-Provera: A progesterone-like drug given by injection that stops ovulation. The effects last for about three months. Monthly injections: Combines two types of hormones, estrogen and progestin, which work to prevent ovulation. Skin patch: Releases the hormones estrogen and progestin into the bloodstream. Diaphragm or cervical cap: A dome-shaped rubber cup with a flexible rim that's inserted through the vagina to cover the cervix before sexual intercourse. Hormonal vaginal contraceptive ring: A ring that's placed inside the vagina around the cervix. It releases the hormones estrogen and progestin. A contraceptive jelly provides added protection. Intrauterine device (IUD): Devices placed in the uterus through the cervix by a doctor. The IUD prevents an egg from being fertilized in the tubes or from attaching to the uterine wall. Intrauterine system (IUS): A small T-shaped device that's placed inside the uterus by a doctor. It releases a small amount of hormones each day to prevent pregnancy. Nonsurgical sterilization: A thin tube is used to thread a tiny, spring-like device through the vagina to the uterus into each fallopian tube. A material in the device causes scar tissue to develop and permanently plug the tubes. Surgery that results in the inability to become pregnant includes the following: Hysterectomy: Removal of the uterus and usually the ovaries and fallopian tube. This is a permanent form of birth control. Tubal ligation or tubal occlusion: Surgery to cut, cauterize, or band the fallopian tubes to prevent the egg from being transported to the uterus. Tubal ligation is designed to be permanent, although certain types sometimes can be reversed. Vasectomy: Cutting or clamping the vas deferens, the tubes that carry the sperm from the testes. The testes still produce sperm, but the sperm die and are absorbed by the body. This is a permanent birth control measure. Methods that have been suggested as preventive, but that may actually present a high risk for pregnancy, include withdrawal before ejaculation and sexual intercourse during menstruation.