From 1987 to 2016, the incidence of stroke associated with pregnancy or the postpartum period rose, according to a retrospective population-based cohort study in Finland published online on April 7 in Neurology.
The incidence of cerebral venous thrombosis, subarachnoid hemorrhage, ischemic stroke, and intracerebral hemorrhage, was 14.5 per 100,000 deliveries and rose 2.2-fold over the 30-year timespan, reported Liisa Karjalainen, MD, of the University of Helsinki and Helsinki University Hospital in Finland, and colleagues.
To prevent incidence of pregnancy-associated stroke, the study authors said, women with predisposing high-risk conditions should be monitored to ensure they are receiving sufficient anticoagulant or antithrombotic medication. Women at increased risk for pre-eclampsia should be screened and treated for hypertensive disorders of pregnancy, and receive counseling for smoking cessation, they added.
“Follow up after delivery should be extended to early postpartum, considering the associated increased risk and age-related risk increase noted amongst older expectant mothers," Dr. Karjalainen and colleagues wrote.
The researchers collected information from the Medical Birth Register in Finland on 1,773,728 deliveries occurring from 1987 to 2016. The mean age of the pregnant women rose from 29 years in 1987 to 1991 to 30.5 years in 2011 to 2016.
Dr. Karjalainen's group combined the Medical Birth Register (MBR) and Hospital Discharge Register to find women with incident stroke, including subarachnoid or intracerebral hemorrhage, ischemic stroke, and cerebral venous thrombosis during puerperium or pregnancy.
The researchers used patient files to confirm cases. In order to compare risk factors, they selected three matched controls for each case using the MBR.
A chart review revealed that pregnancy-associated stroke accounted for 29.6 percent of cases.
From 1987-1991 to 2012-2016, pregnancy associated stroke incidence went up from 11.1 to 25.2 per 100,000 deliveries.
Moreover, from ages 20-24 to ages 40 and older, the incidence increased from 9.8 to 29.9 per 100,000 deliveries by age. The incidence was fivefold greater during the early postpartum period compared to the first trimester.
Maternal mortality was 6.6 percent. In the multivariable-adjusted model, smoking beyond 12 gestational weeks (odds ratio 1.8), hypertensive disorders of pregnancy (OR 4.0), and migraine (OR 16.3) were the most important risk factors for pregnancy-associated stroke.
Limitations of the study include that the findings may not be generalizable as the free-for-all health care inequalities resulting from socioeconomic factors are thought to be less pronounced than in many countries, and the cohort does not include pregnancies involving induced or spontaneous abortion prior to gestational age of 22 weeks, the researchers noted.
Another limitation of the study is that the cohort is small with respect to the overall Finnish population, they added.
Dr. Karjalainen did not report any conflicts of interest.
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Karjalainen L, Tikkanen M, Rantanen K, et al. Stroke in pregnancy and puerperium: Validated incidence trends With risk factor analysis in Finland 1987–2016. Neurology 2021; Epub 2021 Apr 7.