Image for oral contraceptives Since first introduced in the 1960s, the birth control pill ("the pill") has been a popular and extremely effective form of contraception. The pill is easy to use and, when taken correctly, it is 95% to 99.9% successful at preventing pregnancy. But, as with any medicine, there are both risks and benefits.

Unintended Pregnancy

While birth control pills are highly reliable in preventing pregnancy, there is the possibility that you could become pregnant. This is especially true if you miss a dose or do not take the pills regularly. Being overweight or obese may also increase your risk of pregancy. The excess weight may affect how well the pills work in your body.

Blood Clots

Oral contraceptive pills can increase your risk of developing blood clots in the veins in your legs. These can become life threatening if the blood clots leave your legs and travel into you lungs. The risk of blood clots is increased more in people who smoke.

Cholesterol Levels

There are different kinds of birth control pills. Some are combination pills, with estrogen and progestin, while others are "mini-pills" with just progestin. Estrogen may affect triglyceride levels and total cholesterol levels—increasing HDL "good" cholesterol and decreasing LDL "bad" cholesterol. Progestin, though, may cause "good" cholesterol to lower and "bad" cholestorol to rise. But, for most women, these changes in blood levels are not strong enough to have a poor effect on your health.

High Blood Pressure

Taking birth control pills may increase the risk of high blood pressure. This risk may be greater if you have other conditions, like being overweight, having a family history of high blood pressure, or smoking. If you take birth control pills, your doctor will check your blood pressure. If you already have high blood pressure, talk to your doctor about other contraceptive options.

Cardiovascular Disease

Women aged 35 or older who smoke heavily and take birth control pills have an increased risk of having a heart attack or stroke. You may have an even greater risk if you have other risk factors (eg, family history of cardiovascular disease, high cholesterol, high blood pressure). If you want to take birth control pills, you should first quit smoking, since smoking increases your chance of developing many other health problems.

Cancer

Taking birth control pills for many years may increase the risk of certain types of cancer, like cervical cancer. Researchers are still investigating the link between birth control pills and breast cancer. Some studies have found that there is an increased risk, while others studies have come to the opposite conclusion. According to the National Cancer Institute, there appears to be a slight increase in risk, but the risk level goes back to normal after 10 years of stopping birth control pills. It is important to remember that there are many other risk factors for cancer. If you are at high risk for breast cancer (eg, having certain types of genes or a family history) or other types of cancer, talk to you doctor about the best contraceptive for you.