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 Information
The 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.
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