Subarachnoid Hemorrhage During Pregnancy and Puerperium: A Population-Based Study

BACKGROUND

Pregnancy-related subarachnoid hemorrhage (pSAH) is rare, but it causes high mortality and morbidity. Nevertheless, data on pSAH are limited. The objectives here were to examine the incidence trends, causes, risk factors, and outcomes of pSAH in a nationwide population-based cohort study in Finland covering 30 years.

METHODS

We performed a retrospective population-based cohort study and nested case-control study in Finland for the period 1987-2016 (Stroke in Pregnancy and Puerperium in Finland). The Medical Birth Register was linked to the Hospital Discharge Register to identify women with incident stroke during pregnancy or puerperium. A subcohort of women with SAH is included in this analysis. The temporal connection of SAH to pregnancy and clinical details were verified from patient records.

RESULTS

The unadjusted incidence of pSAH was 3.21 (95% CI, 2.46-4.13) per 100 000 deliveries. No significant increase occurred in the incidence throughout the study period. However, the age of the mother had a significant increasing effect on the incidence. In total, 77% of patients suffered an aneurysmal pSAH, resulting in death in 16.3% of women and with only 68.2% achieving good recovery (modified Rankin Scale score 0-2) at 3 months. Patients with nonaneurysmal pSAH recovered well. The significant risk factors for pSAH were smoking (odds ratio, 3.27 [1.56-6.86]), prepregnancy hypertension (odds ratio, 12.72 [1.39-116.46]), and pre-eclampsia/eclampsia (odds ratio, 3.88 [1.00-15.05]).

CONCLUSIONS

The incidence of pSAH has not changed substantially over time in Finland. The majority of pSAH cases were aneurysmal and women with aneurysm had considerable mortality and morbidity. Counseling of pregnant women about smoking cessation and monitoring of blood pressure and symptoms of pre-eclampsia are important interventions to prevent pSAH.

Stroke in Pregnancy and Puerperium: Validated Incidence Trends With Risk Factor Analysis in Finland 1987-2016

OBJECTIVE

To investigate whether previously reported increasing incidence of pregnancy-associated stroke (PAS) is observed in chart-validated register data in Finland. In an exploratory analysis, we studied risk factors for PAS.

METHODS

We performed a retrospective population-based cohort study and nested case-control study in Finland from 1987 to 2016. The Medical Birth Register (MBR) was linked to the Hospital Discharge Register to identify women with incident stroke (ischemic stroke, cerebral venous thrombosis, intracerebral or subarachnoid hemorrhage) during pregnancy or puerperium. Cases were verified from patient records. Incidence of PAS over the study period in 5-year age groups and pregnancy/postpartum period was calculated per number of deliveries. Three matched controls were selected for each case from MBR to compare risk factors.

RESULTS

After chart review, 29.6% (257 of 868) of cases were PAS. The incidence of PAS was 14.5 (95% confidence interval [CI] 12.8-16.3) per 100,000 deliveries. Incidence increased from 11.1 to 25.2 per 100,000 deliveries from 1987 to 1991 to 2012 to 2016 (p < 0.0001). Incidence increased by age from 9.8 to 29.9 per 100,000 deliveries from 20 to 24 years to >40 years of age (p < 0.0001). During the early postpartum period, incidence was 5-fold greater compared to the first trimester. Maternal mortality was 6.6%. In the multivariable-adjusted model, smoking beyond 12 gestational weeks (odds ratio [OR] 1.8, 95% CI 1.2-2.7), migraine (OR 16.3, 95% CI 5.3-49.8), and hypertensive disorders of pregnancy (OR 4.0, 95% CI 2.5-6.3) were the most important risk factors for PAS.

CONCLUSION

PAS incidence is increasing, stressing the importance of careful pregnancy surveillance and risk factor management, particularly in older expectant mothers and extending to puerperium.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that smoking beyond 12 gestational weeks, migraine, and hypertensive disorders of pregnancy are associated with an increased risk of PAS.