Women at higher risk for stroke during postpartum
Women in the postpartum period are more likely to experience stroke than
women of childbearing age who are not pregnant, Emory neurologist Barney
J. Stern and others reported recently in a New England Journal of Medicine
article, "Pregnancy and the Risk of Stroke."
The study is the most comprehensive to date evaluating pregnancy stroke
Researchers evaluated the occurrence of stroke during 234,014 pregnancies
during 1988 and 1991. They report that of 192 strokes caused by cerebral
infarctions, 17 were related to pregnancy, and that of 62 strokes caused
by intracerebral hemorrhages among the women begin studied, 14 were related
to pregnancy. The researchers estimate that about 8.1 strokes occur during
every 100,000 pregnancies.
Stern, who is professor of neurology at the School of Medicine and is on
staff at the Emory Stroke Center, is the paper's second author. His former
Baltimore colleague, Steven J. Kittner of the University of Maryland, is
"The risks of both cerebral infarction and intracerebral hemorrhage
are increased in the six weeks after delivery but not during pregnancy itself,"
the authors report.
The relative risk of cerebral infarction is 8.7 times higher for women in
the postpartum period than nonpregnant women, and the relative risk for
intracerebral hemorrhage is 28.3 times higher for women in the postpartum
period than nonpregnant women.
"The extremely high relative risk of stroke during the postpartum period
suggests a causal role for the large decrease in blood volume or the rapid
changes in hormonal status that follow a live birth or stillbirth, perhaps
by means of hemodynamic, coagulative or vessel-wall changes," the authors
The researchers also report that the strokes could not have been predicted
in nearly all the patients.
For all but one study patient, stroke associated with pregnancy was the
first sign of an underlying disorder such as arteriovenous malformation
(a brain abnormality) or pre-eclampsia-eclampsia (a toxic condition associated
"With the possible exception of cocaine use in one patient, factors
that strongly predispose patients to stroke were not apparent before pregnancy
in our study," the authors report. "Thus, there is little to suggest
that medical intervention could have prevented these strokes." On the
other hand, "The surprising absence of pregnancy-associated strokes
in women previously recognized as having strong predisposing factors may
be due to the relatively small numbers of women with these conditions, a
low pregnancy rate among those at risk, or the use of effective measures
to prevent stroke in those at risk."
Stern is quick to put the study findings in perspective. "It is important
for women to realize that the vast majority of pregnancies are not complicated
by stroke," he said. "If this rare problem does occur, management
considerations can be quite complex, especially if the stroke were to occur
during pregnancy or labor." The study data were collected as part of
the Baltimore-Washington Cooperative Young Stroke Study.
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