PREGNANCY AND THE RISK OF STROKE

Background It is widely believed that pregnancy increases the risk of stroke, but there are few data available to quantify that risk. Method s We identified all female patients 15 through 44 years of age in cent ral Maryland and Washington, D.C., who were discharged from any of 46 hospitals in the study area in 1988 or 1991. Two neurologists reviewed each case, using data from the women's medical records. We determined whether the women had been pregnant at the time of the stroke or up t o six weeks before it occurred. For purposes of this analysis, the six -week period after pregnancy could begin with an induced or spontaneou s abortion or with the delivery of a live or stillborn child. Results Seventeen cerebral infarctions and 14 intracerebral hemorrhages occurr ed in women who were or had recently been pregnant (pregnancy-related strokes), and there were 175 cerebral infarctions and 48 intracerebral hemorrhages that were not related to pregnancy. For cerebral infarcti on, the relative risk during pregnancy, adjusted for age and race, was 0.7 (95 percent confidence interval, 0.3 to 1.6), but it increased to 8.7 for the postpartum period (after a live birth or stillbirth) (95 percent confidence interval, 4.6 to 16.7). For intracerebral hemorrhag e, the adjusted relative risk was 2.5 during pregnancy (95 percent con fidence interval, 1.0 to 6.4) but 28.3 for the postpartum period (95 p ercent confidence interval, 13.0 to 61.4). Overall, for either type of stroke during or within six weeks after pregnancy, the adjusted relat ive risk was 2.4 (95 percent confidence interval, 1.6 to 3.6), and the attributable, or excess, risk was 8.1 strokes per 100,000 pregnancies (95 percent confidence interval, 6.4 to 9.7). Conclusions The risks o f both cerebral infarction and intracerebral hemorrhage are increased in the six weeks after delivery but nor during pregnancy itself. (C) 1 996, Massachusetts Medical Society.