What is blood pressure?
Blood pressure is a measure of the force of blood against the walls of your arteries (or blood vessels) as blood flows through the body. Blood pressure is given as two numbers. The first or top number is the systolic pressure – the pressure of the blood in the vessels as the heart beats. The second or bottom number is the diastolic pressure — the pressure in the vessels as the heart relaxes between beats. Blood pressure is measured in millimeters of mercury (mm Hg), reflecting how much the pressure in your arteries would raise a column of mercury. A blood pressure of 120 mm Hg systolic and 80 mm Hg diastolic is written 120/80 (“120 over 80”).
Blood Pressure Categories
|Classification of Blood Pressure For Adults|
|Category||Systolic (mm Hg)||Diastolic (mm Hg)|
|Normal||Less than 120||and||Less than 80|
|Stage 1 High BP||140-159||or||90-99|
|Stage 2 High BP||160 or higher||or||100 or higher|
What is high blood pressure?
Normal blood pressure is less than 120 mm Hg systolic and 80 mm Hg diastolic. For adults, high blood pressure ( hypertension) is when blood pressure is higher than 140 mm Hg systolic and/or 90 mm Hg diastolic. High blood pressure is dangerous because it makes the heart work too hard and leads to hardening of the arteries, increasing your risk of heart disease and stroke
What is prehypertension?
If your blood pressure is higher than 120/80 but lower than 140/90, you have prehypertension. This means that you don’t have high blood pressure yet, but are very likely to develop it in the future.
How does high blood pressure affect heart disease risk?
High blood pressure increases your risk of dying early or having a heart attack, stroke, or heart failure. For each rise in blood pressure of 20 mm Hg systolic (top) or 10 mm Hg diastolic (bottom), your risk of heart disease doubles. It is estimated that controlling blood pressure could prevent one third of heart disease problems in women. Women and men with high blood pressure at age 50 develop heart disease 7 years earlier and die on average 5 years earlier than people with normal blood pressure at this age.
High blood pressure damages your heart in a number of ways. It can cause your heart to become enlarged as a result of being overworked. Eventually, the heart gets weaker and cannot pump blood as effectively through your body. An enlarged, thickened heart can cause irregular heart beats (arrhythmia). High blood pressure also contributes to the buildup of fatty plaque in the arteries. It makes your arteries stiffer and less flexible, making it harder for blood to flow through them easily.
High blood pressure that is not controlled affects not only your heart and blood vessels, but other organs as well. It can cause impaired vision and blindness, and kidney damage that may require dialysis or a kidney transplant.
What is “white coat hypertension”?
Many people become anxious when visiting their healthcare provider, causing their blood pressure to temporarily rise. This condition is called white coat hypertension (the name refers to the white coats that doctors usually wear) and is more common in women than men.
If your healthcare provider thinks you may have white coat hypertension, you may be asked to wear a device called an ambulatory blood pressure monitor, or Holter monitor. It is usually worn for 24 hours in order to see what your blood pressure is like outside of the hospital, office, or clinic and in a more relaxed environment.
Women with white coat hypertension are not at the same increased risk for heart disease as women with traditional high blood pressure. However, they may have a slightly higher risk than women who don’t have white coat hypertension.
What other types of hypertension are there?
Many older people develop a form of high blood pressure called isolated systolic hypertension (ISH). This occurs when the top (systolic) number is high but the bottom (diastolic) number is normal.
There are also specific types of high blood pressure that can develop during pregnancy (gestational hypertension and preeclampsia) that are risky for both the mother and baby, and require careful monitoring and treatment. However, these conditions do not increase the risk of heart disease or stroke.
Causes & Who is At Risk
How common is high blood pressure, and who is at risk?
One in 3 American adults has high blood pressure. This includes 36 million women—31% of white women, 45% of African-American women, and 29% of Mexican-American women. Another 28% of all adults have prehypertension. Isolated systolic hypertension affects 30% of women over the age of 65.
There are many factors that affect your risk of developing high blood pressure. Blood pressure tends to increase with age, making you more likely to get high blood pressure as you get older. In people younger than 55 years, more men than women have high blood pressure. After age 55, more women than men have high blood pressure.
Your risk of developing high blood pressure also increases if you:
- Are overweight or obese
- Don’t get much exercise
- Have an unhealthy diet
- Have a family history of high blood pressure
- Are African American
- Have diabetes
- Have high cholesterol
- Drink too much alcohol
What causes high blood pressure?
Although there are many factors that increase your chance of developing high blood pressure, in most people the basic causes of high blood pressure are unknown. Less than 10% of high blood pressure cases are caused by another medical problem, such as kidney disease. This type of high blood pressure is called secondary hypertension. It is usually temporary and goes away when the original medical problem is corrected.
Can hormone therapy and birth control affect blood pressure in women?
While it is unusual, your blood pressure may go up if you are taking birth control pills or hormone therapy (HT) for menopausal symptoms, so it is important to have your blood pressure checked regularly.
Why are African Americans more likely to develop high blood pressure?
African Americans tend to develop high blood pressure at an earlier age than people of other races.6 Their high blood pressure is also more severe and results in more complications. Both genetics and social factors are probably responsible.
One theory is that, to survive in a hot climate, Africans developed the ability to sweat a lot to cool down. When the body sweats, you lose not only water, but salt as well: to make up for the lost salt, Africans have a strong taste for salt and their kidneys retain more salt than other races. While these adaptations enabled Africans to survive in a hot climate where salt was scarce, in people of African descent who have access to a high-salt Western diet, they result in high blood pressure.
In addition, African-American women are more likely than women of other races to be physically inactive and overweight or obese—risk factors for high blood pressure. Economically disadvantaged African Americans are also less likely to have health insurance or get frequent checkups, allowing high blood pressure to develop unchecked and causing more complications. When African Americans with high blood pressure receive similar care to white patients, the race gap in complications is reduced or disappears.
Measuring Blood Pressure
What are the signs of high blood pressure?
High blood pressure is called “the silent killer” because it does not have any signs or symptoms. Many people have high blood pressure for years without knowing it. Having your blood pressure measured is the only way to tell if you have high blood pressure. You should have your blood pressure measured at least once every 2 years, and at least once a year if you already have prehypertension. Based on your specific risk factors, your doctor may recommend that you have your blood pressure checked more often.
How is blood pressure measured?
Blood pressure is measured by your healthcare provider using a device called a sphygmomanometer (sfig·mo·ma·nom·e·ter). A rubber cuff is wrapped around your upper arm and inflated, stopping blood flow momentarily. The cuff is attached to a gauge with blood pressure values. Next, air in the cuff is released, and the person measuring the blood pressure listens with a stethoscope. When the blood starts to pulse through the artery, it makes a sound. Sounds continue to be heard until pressure in the artery exceeds the pressure in the cuff. The person listens and watches, and then records two measurements. Systolic pressure is the pressure of the blood flow when the heart beats (the pressure when the first sound is heard). Diastolic pressure is the pressure between heartbeats (the pressure when the last sound is heard).
To make sure you get the most accurate possible reading:
- Don’t drink coffee or smoke for 30 minutes before the blood pressure check
- Go to the bathroom prior to having your blood pressure checked — a full bladder can change your reading
- Sit still for 5 minutes with your back supported and your feet flat on the ground just before having your blood pressure checked
Can I measure my own blood pressure?
If you have been diagnosed with high blood pressure, your doctor may recommend that you measure your blood pressure at home using over-the-counter blood pressure measuring devices, available in pharmacies and discount chain stores. These include the standard type with a blood pressure cuff and a stethoscope, as well as more advanced monitors with a digital readout. Your healthcare provider or pharmacist can help you choose the right type of blood pressure device for you and teach you how to use it.
Follow the tips above to get the best possible home blood pressure reading, and make sure to:
- Rest your arm on a table at the level of your heart
- Take at least two readings 2 or more minutes apart, and average the results
If you measure your blood pressure at home, keep a record of the numbers and take it with you each time you see your health care provider.
Prevention & Treatment
How can I prevent high blood pressure?
If you don’t have high blood pressure now, you can take steps to prevent it. While you can’t do anything about some risk factors for high blood pressure (such as age, family history, and race), there are other risk factors you can reduce by adopting a heart-healthy lifestyle. These include being overweight, being inactive, and not exercising regularly, and eating a diet high in salt and fat. You can help prevent high blood pressure by taking the following steps:
- Control your weight, or lose weight if you are overweight. Losing even 10 pounds will help. BMI Calculator
- Exercise regularly – 30 minutes of moderate exercise a day most days of the week is best.
- Follow a healthy eating plan, such as the Dietary Approaches to Stop Hypertension (DASH) diet. Eat more fruits and vegetables and low-fat or nonfat dairy products, and limit the amounts of saturated fat, total fat, and cholesterol.
- Limit your daily intake of sodium to less than 2,400 mg (about ¾ teaspoon of salt). This includes the salt you add from the salt shaker and the salt that is already in prepared foods. Read product labels so you know what you are eating. If you would like to try a salt substitute, talk with your healthcare provider first because they may be harmful to people with certain medical conditions.
- Aim to consume at least 3,500 mg of potassium per day. Foods rich in potassium include bananas, cantaloupe, broccoli, and peas.
- If you drink alcohol, do so in moderation. For women that means no more than 1 drink per day, equivalent to 5 ounces of wine, 12 ounces of beer, or 1.5 ounces (a “shot”) of 80 proof liquor.
- If you are taking birth control pills or hormone therapy, get regular blood pressure checks from your healthcare provider to find and control a blood pressure problem.
- If you smoke, quit. While smoking doesn’t cause high blood pressure, it can temporarily raise blood pressure. In addition, smoking causes hardening of the arteries and increases your risk for heart disease.
Talk with your healthcare provider if you need help with these steps or have any questions or concerns.
How is high blood pressure treated?
Although 3 out of 4 women with high blood pressure know they have it, only one 1 of 3 women takes steps to control it. Women are less likely to have their blood pressure under control than men.
For many people with high blood pressure, lifestyle changes including a healthy diet and exercise can reduce blood pressure to normal levels. For others, particularly those with heart disease, medication may also be needed. There are many kinds of medications used to treat high blood pressure, and most people require two or more kinds to lower their blood pressure to a healthy level. To learn more about these medications, visit the High Blood Pressure Medicine section of this website.
If you require medication, make sure you continue making heart-healthy lifestyle changes. These changes help the medication work better, and over time you may be able to reduce the doses of medication. In most cases, high blood pressure can be controlled with a healthy lifestyle and medication.
Pregnancy & High Blood Pressure
What should I know about pregnancy and high blood pressure?
About 5% to 10% of pregnancies experience complications due to high blood pressure. High blood pressure during pregnancy is the second largest cause of maternal death, responsible for 15% of all that occur during pregnancy.
There are two ways high blood pressure can affect pregnancy. The first is when you have high blood pressure and later become pregnant. This is referred to as chronic hypertension during pregnancy. Most women with chronic hypertension during pregnancy are at low risk for heart disease during pregnancy. However, in some cases it can cause serious problems, such as preeclampsia, that can threaten the lives of both the mother and the fetus. Certain types of blood pressure medicines can cause birth defects, so be sure to talk to your doctor if you have high blood pressure and plan to become pregnant so your medication can be adjusted if necessary.
There are also high blood pressure disorders that occur in women who may not have had high blood pressure before they became pregnant. These are preeclampsia-eclampsia and gestational hypertension.
What is preeclampsia?
Preeclampsia (“toxemia of pregnancy”) is diagnosed if the mother has high blood pressure and protein in the urine. The protein is a sign of kidney problems. Preeclampsia usually occurs after the 20th week of pregnancy and can result in seizures (called eclampsia). It is a very serious condition that occurs in about 5% of pregnancies, and risks include death for the mother and premature birth, stillbirth, and low birth weight for the baby. Risk factors for preeclampsia include older age, high blood pressure, first pregnancies, and multiple births. There is no way to prevent preeclampsia and it can only be cured by delivering the baby. During pregnancy, it can be managed with medications to lower blood pressure and prevent convulsions. The problems associated with preeclampsia, including high blood pressure, usually go away within 6 weeks of delivery.
What is gestational hypertension?
Gestational hypertension is high blood pressure (greater than 140/90) that is diagnosed for the first time after midpregnancy. Usually, this condition is not dangerous and blood pressure returns to normal within 3 months after delivery. If blood pressure remains high more than 3 months after delivery, it is diagnosed as chronic high blood pressure.
Preeclampsia-eclampsia and gestational hypertension are not associated with an increased risk of heart disease or stroke. However, women who have gestational hypertension have an increased risk of developing high blood pressure later in life.