Preeclampsia
Risk in Pregnancy Detected
High blood levels of two proteins may tip physicians off
to the development of preeclampsia, a dangerous and often unpredictable complication
of pregnancy, says a report in the New England Journal
of Medicine.
" In general, you need high [blood] levels of both these
proteins to get severe preeclampsia," says Dr. Richard J. Levine at the National
Institutes of Health (NIH). Dr. Levine, the lead researcher on the study, is a senior
investigator at the National Institute of Child Health
and Human Development (NICHD), part of the NIH.
Preeclampsia affects up to 8 percent of pregnancies around
the world and can lead to premature delivery and the need for a Cesarean section.
The condition results in a sudden spike in high blood pressure
and a rise in protein in the urine.
One of the major challenges with preeclampsia is that it
has been tough for physicians to predict who might be at risk.
While the study results are preliminary, Dr. Levine and
others caution that "there is [now] hope for developing a predictive test as
well as a diagnostic one."
In the study, Dr. Levine compared data from five groups
of women - those with preterm preeclampsia, those with preeclampsia at term
(37 weeks), those with pregnancy-associated high blood pressure, those with
normal pressure who delivered infants small for gestational age, and women
with normal blood pressure who delivered infants who were not small for gestational
age.
Four of the groups included 120 women each, while the group
with preterm preeclampsia included 72 women.
All had been participants in the Calcium for Preeclampsia
Prevention (CPEP) trial, a study conducted from 1992 to 1995 to evaluate the
effects of daily calcium supplements in reducing preeclampsia (the supplements
did not prove effective).
Dr. Levine's team examined blood specimens taken and stored
during the CPEP study, comparing levels of two specific blood proteins, endoglin
and sFlt1.
Comparing women who had preeclampsia to women with stable
blood pressure, Dr. Levine says protein levels "started going up two or three
months before they developed the disease. So that gives us reason to believe
we can identify women who will subsequently develop preeclampsia."
The first protein, soluble endoglin, began to rise in the
17th to 20th week of pregnancy in women who developed preterm preeclampsia.
For women who developed preeclampsia later on, at full-term, levels started
to climb at weeks 25 to 28.
Those who developed high blood pressure later (but not the
protein in the urine associated with preeclampsia) had their levels rise in
the 33rd through the 36th week of pregnancy.
The second protein studied was soluble fms-like tyrosine
kinase 1, or "sFlt1."
"Those who developed preeclampsia had increased levels of
this protein,” reports Dr. Levine. “They also had reduced levels
of another substance called placental growth factor, or PlGF. Those who got
preeclampsia at term and those who had gestational high blood pressure had
a rise in the soluble endoglin and an increase in their sFlt1-to-PlGF ratio.
"We haven't investigated this enough to say how often it
occurs," says Dr. Levine. Nor can they yet say how much the risk of preeclampsia
rises with each increase in protein levels.
One expert praises the study. "It's great," says Dr. Brian
Brost at the Mayo Clinic in Rochester, Minn. He says science is "getting closer
and closer" to understanding and predicting preeclampsia.
Earlier this year, Dr. Brost's team identified an association
between preeclampsia and a third protein, HtrA, which is found in placental
tissues.
In an editorial accompanying the study, Drs. Marshall Lindheimer
of the University of Chicago and Jason Umans of Georgetown University note
that the "authors now have strong evidence to suggest the usefulness of these
proteins in predicting preeclampsia."
But they said that the data was from samples stored for
about 10 years. They questioned if those samples had remained stable over such
a long time.
Dr. Levine says he believes the blood samples did retain
their integrity, since they showed no signs of deterioration.
Until more is known about preeclampsia, however, there is
not much a woman can do to minimize her risk, says Dr. Brost.
"Currently, nothing is proven to be of marked benefit," he
says.
Women should be sure to adhere to their prenatal visit schedule,
he notes, as close monitoring can help pick up preeclampsia early.
If the condition is diagnosed early, a physician may prescribe
medicine to lower blood pressure and buy some time. Or, the physician might
decide to deliver the baby, if the woman is nearing term.
Always consult your physician for more information.
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According to the American Academy
of Family Physicians (AAFP), preeclampsia (say "pre-ee-clamp-see-ah"),
which is also called toxemia, is a problem that occurs in some women during
pregnancy.
It can happen during the second half of pregnancy. A physician
will look for the following signs of preeclampsia: high blood pressure, swelling
that does not go away, and large amounts of protein in the urine.
Preeclampsia is more common in a woman's first pregnancy
and in women whose mothers or sisters had preeclampsia, states the AAFP.
The risk of preeclampsia is higher in women carrying multiple
babies, in teenage mothers, and in women older than age 40.
Other women at risk include those who had high blood pressure
or kidney disease before they became pregnant. The cause of preeclampsia
is not known.
If your physician sees that your blood pressure is high,
he or she will watch you closely for changes that could mean you have preeclampsia.
In addition to high blood pressure, women who have preeclampsia
also have excessive swelling. They may also have protein in their urine.
Many women with high blood pressure during pregnancy do
not have protein in their urine or extreme swelling, and do not get preeclampsia.
Swelling alone does not necessarily mean you have preeclampsia,
according to the AAFP.
Some swelling is normal during pregnancy. For example,
your rings or shoes might become too tight. Swelling is more serious if it
does not go away after resting, if it is very obvious in your face and hands,
or if it is a rapid weight gain of more than five pounds in a week.
No one test diagnoses preeclampsia.
Your blood pressure will be checked during each physicians
visit. A significant rise in your blood pressure can be an early sign that
you might have preeclampsia.
A urine test can tell if there is protein in your urine.
Your doctor may order certain blood tests, which may show
if you have preeclampsia. If you have signs of preeclampsia, your physician
may want to see you at least once a week and possibly every day.
Preeclampsia can prevent the placenta (which gives oxygen
and nutrition to your baby) from getting enough blood. If the placenta does
not get enough blood, your baby gets less oxygen and nutrition. This can
cause low birth weight and other problems for the baby.
Most women with preeclampsia still deliver healthy babies.
A few develop a condition called eclampsia (seizures caused by toxemia),
which is very serious for the mother and baby, or other serious problems.
Fortunately, states the AAFP,
preeclampsia is usually detected early in women who get regular prenatal
care, and most problems can be prevented.
Always consult your physician for more information.
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