What hormones are in birth control pills?
Birth control pills (also called oral contraceptives or hormonal contraceptives) are the most commonly used form of birth control in the United States. Most common birth control pills contain a combination of two hormones, estrogen and progestin (although some pills contain only progestin).
Most women take low-dose birth control pills, which have 50 micrograms or less of estrogen. Modern birth control pills contain 20 to 50 micrograms of estrogen – more than 50 micrograms is considered “high-dose.” Older birth control pills contained up to 5 times as much estrogen and 10 times as much progestin as modern pills. Because studies found that these older pills caused serious complications including stroke, heart attack, and blood clots in the lungs ( pulmonary embolism), the amounts of hormones were reduced.
Do birth control pills affect heart disease risk?
For women who do not have serious risk factors for heart disease, low-dose birth control pills do not pose a risk for heart disease. The same is true for women who wear a birth control patch, another type of hormonal contraceptive, which releases about the same amount of estrogen as low-dose birth control pills. Older birth control pills were found to increase the risk of heart attack by as much as 2.5 times, but evidence indicates that newer pills are safe.1, 2
Women who use high-dose pills (>50 micrograms of estrogen) are more likely to have a heart attack or stroke because blood clots are more likely to form in the blood vessels.3 There is controversy over whether the modern low-dose pill (<50 micrograms of estrogen) increases the risk of stroke, but if it does, the increase is very small. In women younger than 35 who do not smoke or have high blood pressure, the risk of stroke is 10 per 100 000 women, and this increases only to about 13 per 100 000 in women taking birth control pills.4
What risk factors increase the risk of problems with birth control pills?
In women with certain heart disease risk factors, taking birth control pills can increase the risk of heart problems. You may want to consider an alternative method of birth control if you:
- Have high blood pressure
- Are overweight or obese
- Have diabetes
- Have been diagnosed with heart disease, stroke, or blood clots
- Have a family history of heart disease
Women who smoke while using oral contraceptives have a higher risk of serious cardiovascular problems such as blood clots, particularly if they are older than 35 years of age.
Blood levels of glucose (sugar) sometimes change dramatically in women who take birth control pills. If you are diabetic or have a close relative who is, you should have your blood sugar monitored closely when starting the pill.
If you have had problems with blood clots, a heart attack, or a stroke, or if you have had any kind of cardiovascular disease, hormonal contraceptives may not be a safe option for you. Be sure to discuss your medical history with your healthcare provider, including whether you have taken high-dose birth control pills in the past, before taking hormonal contraceptives.
Do birth control pills increase blood pressure?
Taking oral contraceptives slightly raises blood pressure, causing some women to develop high blood pressure; if you take the pill or wear the patch, you should have your blood pressure checked at least once a year. High blood pressure occurs 2 to 3 times more often in women on the pill than in women who do not take it — especially in women who are obese, are older than 35, have mild kidney disease or a family history of high blood pressure, or have had high blood pressure during pregnancy.1 If you use birth control pills and your blood pressure becomes high, you should talk to your healthcare provider about switching to a different method of birth control. Once you stop taking the pill, your blood pressure will return to normal in 3 to 6 months. If you've had high blood pressure in the past but it is under control with high blood pressure medication, you may still be able to take the pill, but your blood pressure will need to be closely monitored.References
1. Tanis BC, van den Bosch MA, Kemmeren JM, et al. Oral contraceptives and the risk of myocardial infarction. N Engl J Med. 2001;345:1787-1793.
2. Spitzer WO, Faith JM, MacRae KD. Myocardial infarction and third generation oral contraceptives: aggregation of recent studies. Hum Reprod. 2002;17:2307-2314.
3. Haemorrhagic stroke, overall stroke risk, and combined oral contraceptives: results of an international, multicentre, case-control study. WHO Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception. Lancet. 1996;348:505-510.
4. Chan WS, Ray J, Wai EK, et al. Risk of stroke in women exposed to low-dose oral contraceptives: a critical evaluation of the evidence. Arch Intern Med. 2004;164:741-747.