DURING POSTPARTUM, WOMEN AT HIGHER RISK FOR STROKE, REPORT EMORY AUTHOR AND OTHERS IN NEJM

October 15, 1996

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Women in the postpartum period are more likely to experience stroke than women of childbearing age who are not pregnant, Emory University neurologist Barney J. Stern, M.D., and others reportd 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 risk.

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.

Dr. Stern, who is professor of neurology at the Emory University 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, M.D., of the University of Maryland, is first author.

"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 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 preeclampsia-eclampsia (a toxic condition associated with pregnancy).

"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."

Dr. 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 says. "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 was collected as part of the Baltimore-Washington Cooperative Young Stroke Study.

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