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High Blood Pressure During Pregnancy
Blood pressure is the pressure in the vessel that carry blood through the
body. Normal levels are key to good health. When pressure
becomes too high, it is known as hypertension. This can pose health
risks at any time. It is even more of a risk during pregnancy.
If it is not treated, it can cause severe problems for both mother and baby.
If you are pregnant and have any of the risk factors that may lead to high
blood pressure, you may need special care.
Blood
pressure is vital for the body's circulatory system-the
heart, arteries, and veins-to function. It is
created in part by the steady beating of the heart.
Each time the heart contracts or squeezes, it pumps blood
into the arteries. The arteries carry the blood to
the body's organs. The veins return it to the heart.
Small arteries, called arterioles, also effect blood
pressure. These blood vessels are lined with a layer
of muscle. When the blood pressure is normal, this
muscle is relaxed and the arterioles are dilated (open) so
that blood can flow through them easily. However, if
a signal is sent to increase the blood pressure, the
muscle layer tightens and the arterioles narrow.
This makes it harder for the blood to flow. The
pressure then rises in the arteries. Imagine that an
arteriole is the nozzle on a hose. When the nozzle
is open, the water can escape, so the pressure in the hose
is normal. When it is closed, the water is trapped.
The pressure in the hose rises, but less water comes out.
Blood pressure is checked with a stethoscope and a device
made of a pressure gauge and a cuff that inflates. A
blood pressure reading has two numbers. Each number
is separated by a slash: 110/80, for instance. (You
may hear this referred to as "110 over 80.") The
first number is the pressure in the arteries when the
heart contracts. This is called the systolic
pressure. The second number is the pressure in the
arteries when the heart relaxes between contractions.
This is the diastolic pressure. Blood pressure
changes from person to person. It changes often
during the day. It can rise if you are excited or if
you exercise. Most often, it falls when you are
resting. These short-term changes in blood pressure
are normal. It is only when a person's blood
pressure stays high for some time that it may signal a
problem. In most nonpregnant women, readings less
than 130/80 are normal. If you are pregnant and your
systolic pressure is 140 or the diastolic pressure is 90,
it is too high. Because of the normal ups and downs
in blood pressure, if you have one high reading, another
reading may be taken again later to see if it is
your normal level. Your normal blood pressure can be
an average of a number of readings taken at rest.
TYPES OF
HIGH BLOOD PRESSURE
When high blood pressure has been present for some time
before pregnancy, it is known as chronic hypertension.
This condition remains during pregnancy and after the
birth of the baby. When high blood pressure occurs
for the first time during pregnancy, it is known as
pregnancy-induced hypertension (PIH). Both types can
pose a risk during pregnancy. If high blood pressure
is controlled, the risks are reduced.
If it is not treated, chronic hypertension can lead to
health problems such as heart failure or stroke.
Women with chronic hypertension who took medication to
control their blood pressure before they were pregnant
often keep on taking it during pregnancy under their
doctor's care. If you take medication to control
your blood pressure, ask your doctor if it is safe to use
during pregnancy.
PREGNANCY-INDUCED
HYPERTENSION
Pregnancy-induced
hypertension may occur some time after the 20th week of
pregnancy. It goes away soon after the baby is born.
With PIH, high blood pressure and other problems are
present. Women with chronic hypertension are at
increased risk of developing PIH. Pregnant women
should be aware of the symptoms of PIH. They are not
always easy to detect. A pregnant woman could have
PIH for weeks and not know it. The serious risks of
high blood pressure in pregnancy can be decreased if it is
found and treated early. The only way to detect PIH
is to measure the blood pressure regularly.
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Warning Signs of Pregnancy-Induced Hypertension
If you
notice any of these symptoms, you should call your
doctor right away:
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A
sudden weight gain of more than about 1 pound a
day |
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Swelling (edema) of the face and hands |
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Severe
or constant headaches |
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Blurred
vision or spots in front of the eyes |
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Pain in
the upper right part of the abdomen |
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In a healthy pregnancy, the fetus receives from the
mother all of the nutrients and oxygen it needs for normal
growth. This happens when the correct amount of the
mother's blood flows through the placenta. This
means that the fetus receives less of the oxygen and
nutrients it needs. This causes the growth of the
fetus to slow. Thus, the growth and the health of
the fetus may be checked using ultrasound
and electronic fetal monitoring. When
PIH is mild, blood pressure rises only slightly. If
the mother's blood pressure is kept under control, she
most likely will have a healthy baby. During
pregnancy, high blood pressure that is mild will not harm
the mother in most cases. When PIH becomes more
severe, other conditions can develop and affect the
mother:
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Her organs-such
as kidneys, liver, brain, and eyes-can become damaged.
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Her heart may be
weakened.
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Her urine tests
may show that there is protein in her urine.
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She may have
swelling (edema) of her hands and face. (It is
normal for pregnant women to have some swelling of the
feet. In women who have high blood pressure, though,
this can be a sign of severe PIH.)
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In extreme
cases, she may have seizures.
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If PIH is not treated, it can be life-threatening for the
mother and baby. The baby may be born to small.
In severe cases, the baby may die. Severe PIH may
require early delivery, even if the baby is not fully
grown. A baby born before 37 weeks may have problems
breathing because its lungs may not be fully developed.
RISK
FACTORS
Most women with PIH have never had high blood pressure.
Doctors do not know why some women get PIH. The do
know that some women are at higher risk than others.
The risk of developing PIH is higher in woman who:
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Have a history
of chronic hypertension or PIH
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Are pregnant for
the first time
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Are over age 40
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Are carrying
more than one fetus
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Have certain
medical conditions such as diabetes or kidney disease
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Pregnancy-induced hypertension occurs more often in women
with a family history of the condition . It also
occurs more often in African-American women. If you
are at high risk for PIH, talk with your doctor about what
might be best for you.
PRENATAL CARE
If a woman knows she has high blood pressure before or
during pregnancy-or if she knows she may be at risk-there
are steps she and her doctor can take to reduce the chance
of severe effects to herself or her baby. For this
reason, the best thing a woman can do is to see her doctor
before pregnancy and get regular prenatal care. At
each prenatal visit, a woman's weight and blood pressure
are taken. This helps detect any changes that might
have occurred. Once the doctor is aware that a
woman's blood pressure is high or that she is at risk for
PIH, she may be checked more often. A urine sample
also is tested for protein in the urine. Its
presence is a sign of PIH. If high blood pressure
occurs, it can be watched closely and treated. This
may prevent other problems. The type of treatment
depends on whether the high blood pressure is mild or
severe and how long a woman has been pregnant.
What You Can Do
Until more is known about what causes PIH, the best
approach is to prevent it from becoming too severe.
If you have chronic high blood pressure or are at
risk for PIH, follow these steps to help make your
pregnancy safer:
Before
Pregnancy:
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If you
have high blood pressure. work with your doctor so
that you can get it under control. |
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Take
medication as prescribed. |
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Lose
weight through diet and exercise, if needed. |
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Check
with your doctor to see if your blood pressure
medication is safe to use during pregnancy. |
During
Pregnancy:
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See your
doctor regularly, starting ass soon as you can, so
that changes in your blood pressure and weight can
be found as soon as they occur. |
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If you
have high blood pressure, kidney disease, or any
other risk factors, be sure to tell your doctor
early in pregnancy. |
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If you
develop any of the warning signs of PIH, tell your
doctor right away. |
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Check
your blood pressure and weight at home, if your
doctor suggests you do so. |
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Tell your
doctor about all the medications you are taking,
including over-the-counter products. |
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When blood pressure rises slightly and the woman is not
near the end of her pregnancy , bed rest may help control
the pressure. Bed rest may be at home or in the
hospital. If the blood pressure does not rise to
dangerous levels, pregnancy will be allowed to continue
until labor beings naturally.
Although most symptoms of PIH can be controlled, the only
real cure for PIH is having the baby. The decision
to deliver the baby depends on both the risks to the
mother and whether the risk to the baby is greater in the
mother's uterus or in a special nursery. The
delivery may occur naturally or labor may be induced
(brought on). Sometimes a cesarean birth is needed.
Before deciding to deliver your baby early, your doctor
may wait to see if your condition improves. During
labor you may be given medication to help prevent seizures
or lower your blood pressure.
Pregnancy-induced hypertension and high blood pressure in
pregnancy can place the mother and baby at risk for severe
problems. If you have chronic hypertension or are at
risk for developing PIH, take steps to reduce the risks to
your baby. You will need special care and may have
to see your doctor more often. Working with your
doctor to control your blood pressure level will help
improve your chances of having a healthy baby.
ACOG PATIENT EDUCATION
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Chicago Maternal-Fetal Medicine, S.C.
