High Blood Pressure in Pregnancy: NHLBI
Article title: High Blood Pressure in Pregnancy: NHLBI
Conditions: High Blood Pressure, pregnancy, Preeclampsia, gestational hypertension
Source: NHLBI
High Blood Pressure in Pregnancy
What Is High Blood Pressure?Blood pressure is the amount of
force exerted by the blood against the walls of the arteries. A person's blood
pressure is considered high when the readings are greater than 140 mm Hg
systolic (the top number in the blood pressure reading) or 90 mm Hg diastolic
(the bottom number). In general, high blood pressure, or hypertension,
contributes to the development of coronary heart disease, stroke, heart failure
and kidney disease.
What Are the Effects of High Blood Pressure in Pregnancy?
Although
many pregnant women with high blood pressure have healthy babies without serious
problems, high blood pressure can be dangerous for both the mother and the
fetus. Women with pre-existing, or chronic, high blood pressure are more likely
to have certain complications during pregnancy than those with normal blood
pressure. However, some women develop high blood pressure while they are
pregnant (often called gestational hypertension).
The effects of high
blood pressure range from mild to severe. High blood pressure can harm the
mother's kidneys and other organs, and it can cause low birth weight and early
delivery. In the most serious cases, the mother develops preeclampsia--or
"toxemia of pregnancy"--which can threaten the lives of both the mother and the
fetus.
What Is Preeclampsia?
Preeclampsia is a condition that
typically starts after the 20th week of pregnancy and is related to increased
blood pressure and protein in the mother's urine (as a result of kidney
problems). Preeclampsia affects the placenta, and it can affect the mother's
kidney, liver, and brain. When preeclampsia causes seizures, the condition is
known as eclampsia--the second leading cause of maternal death in the U.S.
Preeclampsia is also a leading cause of fetal complications, which include low
birth weight, premature birth, and stillbirth.
There is no proven way to
prevent preeclampsia. Most women who develop signs of preeclampsia, however, are
closely monitored to lessen or avoid related problems. The only way to "cure"
preeclampsia is to deliver the baby.
How Common Are High Blood
Pressure and Preeclampsia in Pregnancy?
High blood pressure problems
occur in 6 percent to 8 percent of all pregnancies in the U.S., about 70 percent
of which are first-time pregnancies. In 1998, more than 146,320 cases of
preeclampsia alone were diagnosed.
Although the proportion of pregnancies
with gestational hypertension and eclampsia has remained about the same in the
U.S. over the past decade, the rate of preeclampsia has increased by nearly
one-third. This increase is due in part to a rise in the numbers of older
mothers and of multiple births, where preeclampsia occurs more frequently. For
example, in 1998 birth rates among women ages 30 to 44 and the number of births
to women ages 45 and older were at the highest levels in 3 decades, according to
the National Center for Health Statistics. Furthermore, between 1980 and 1998,
rates of twin births increased about 50 percent overall and 1,000 percent among
women ages 45 to 49; rates of triplet and other higher-order multiple births
jumped more than 400 percent overall, and 1,000 percent among women in their
40s.
Who Is More Likely to Develop Preeclampsia?
- Women with chronic hypertension (high blood pressure before becoming
pregnant).
- Women who developed high blood pressure or preeclampsia during a previous
pregnancy, especially if these conditions occurred early in the pregnancy.
- Women who are obese prior to pregnancy.
- Pregnant women under the age of 20 or over the age of 40.
- Women who are pregnant with more than one baby.
- Women with diabetes, kidney disease, rheumatoid arthritis, lupus, or
scleroderma.
How Is Preeclampsia Detected?Unfortunately,
there is no single test to predict or diagnose preeclampsia. Key signs are
increased blood pressure and protein in the urine (proteinuria). Other symptoms
that seem to occur with preeclampsia include persistent headaches, blurred
vision or sensitivity to light, and abdominal pain.
All of these
sensations can be caused by other disorders; they can also occur in healthy
pregnancies. Regular visits with your doctor help him or her to track your blood
pressure and level of protein in your urine, to order and analyze blood tests
that detect signs of preeclampsia, and to monitor fetal development more
closely.
How Can Women with High Blood Pressure Prevent Problems
During Pregnancy?If you are thinking about having a baby and you have
high blood pressure, talk first to your doctor or nurse. Taking steps to control
your blood pressure before and during pregnancy--and getting regular prenatal
care--go a long way toward ensuring your well-being and your baby's health.
Before becoming pregnant:
- Be sure your blood pressure is under control. Lifestyle changes such as
limiting your salt intake, participating in regular physical activity, and
losing weight if you are overweight can be helpful.
- Discuss with your doctor how hypertension might affect you and your baby
during pregnancy, and what you can do to prevent or lessen problems.
- If you take medicines for your blood pressure, ask your doctor whether you
should change the amount you take or stop taking them during pregnancy.
Experts currently recommend avoiding angiotensin-converting enzyme (ACE)
inhibitors and Angiotensin II (AII) receptor antagonists during pregnancy;
other blood pressure medications may be OK for you to use. Do not, however,
stop or change your medicines unless your doctor tells you to do so.
While you are pregnant:
- Obtain regular prenatal medical care.
- Avoid alcohol and tobacco.
- Talk to your doctor about any over-the-counter medications you are taking
or are thinking about taking.
Does Hypertension or Preeclampsia
During Pregnancy Cause Long-Term Heart and Blood Vessel Problems?The
effects of high blood pressure during pregnancy vary depending on the disorder
and other factors. According to the National High Blood Pressure Education
Program (NHBPEP), preeclampsia does not in general increase a woman's risk for
developing chronic hypertension or other heart-related problems. The NHBPEP also
reports that in women with normal blood pressure who develop preeclampsia after
the 20th week of their first pregnancy, short-term complications--including
increased blood pressure--usually go away within about 6 weeks after
delivery.
Some women, however, may be more likely to develop high blood
pressure or other heart disease later in life. More research is needed to
determine the long-term health effects of hypertensive disorders in pregnancy
and to develop better methods for identifying, diagnosing, and treating women at
risk for these conditions.
Even though high blood pressure and related
disorders during pregnancy can be serious, most women with high blood pressure
and those who develop preeclampsia have successful pregnancies. Obtaining early
and regular prenatal care is the most important thing you can do for you and
your baby.
For More InformationThe NHBPEP has updated clinical
guidelines on high blood pressure in pregnancy through a coordinating committee
representing more than 45 medical organizations and agencies. NHBPEP is
coordinated by the National Heart, Lung, and Blood Institute (NHLBI) of the
National Institutes of Health. The Working Group Report on High Blood Pressure
in Pregnancy (NIH Publication No. 00-3029) can be purchased through the NHLBI
Health Information Network at (301) 592-8573 and is available on the NHLBI Web
site at:
"http://www.nhlbi.nih.gov/health/prof/heart/hbp/hbp_preg.htm."
All women--and men--can take steps to prevent or manage hypertension
and other cardiovascular disorders. For more information, visit the National
Heart, Lung, and Blood Institute Web site at www.nhlbi.nih.gov, or call the
NHLBI Information Center at (301) 592-8573.
U.S. Department of Health and Human Services
Public Health
Service
National Institutes of Health
The National Heart, Lung, and
Blood Institute
January 2001
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