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Pregnancy-associated stroke risk higher in younger women

Younger women have a higher risk for stroke during pregnancy and up to 6 weeks postpartum compared with nonpregnant women, according to a recent study published in JAMA Neurology. The increased risk for stroke did not extend to older pregnant women.

“Pregnancy-associated stroke (PAS) affects approximately 34 of 100,000 pregnancies, and the incidence of PAS is increasing,” Eliza C. Miller, MD, from the department of neurology at the College of Physicians and Surgeons, Colombia University, and colleagues wrote. “Although prior studies suggest that older women have an increased risk of PAS ... these investigations rarely include calculated age-specific incidence risk ratios (IRRs) to determine whether stroke risk in older pregnant and postpartum women exceeds stroke risk in nonpregnant women of the same age.”

The researchers conducted a population-based study in New York state to assess age-specific risk for PAS vs. nonpregnancy-associated stroke (NPAS) in predefined age cohorts. Using data compiled from 2003 through 2012, the investigators identified women aged 12 to 55 years with cerebrovascular events and calculated the cumulative incidence rates of PAS and NPAS per 100,000 pregnant/postpartum women in age cohorts of 24 years or younger, 25 to 34, 35 to 44, and 45 years or older.

Out of 19,146 women hospitalized with stroke, 797 (4.2%) were pregnant/postpartum. The incidence of PAS in women aged 12 to 24 years was 14 events per 100,000 pregnant/postpartum women compared with a NPAS incidence of 6.4 per 100,000 nonpregnant women (IRR = 2.2; 95% CI, 1.9-2.6). For women aged 25 to 34 years, the PAS incidence was 21.2 per 100,000 vs. the NPAS incidence of 13.5 per 100,000 (IRR = 1.6; 95% CI, 1.4-1.7).

In older women, the incidence of PAS among those aged 35 to 44 years was 33 per 100,000 vs. 31 per 100,000 for NPAS (IRR = 1.1; 95% CI, 0.9-1.2). Among women aged 45 to 55 years, the incidence of PAS was 46.9 per 100,000 and the incidence of NPAS was 73.7 per 100,000 (IRR = 0.6; 95% CI, 0.3-1.4).

PAS accounted for 18% of strokes in women younger than 35 years compared to 1.4% of strokes in women aged 35 to 55 years. Based on the results, PAS accounted for 15% of strokes in women 12 to 24; 20% in women 25 to 34; 5% in women 35 to 44; and 0.05% in women 45 to 55. Women in the NPAS group had more vascular risk factors compared with women in the PAS group, including chronic hypertension, diabetes, and active smoking. They also had higher mortality rates.

“These results have potential implications for research aimed at better characterizing and preventing PAS and clinically in terms of counseling patients,” Miller and colleagues concluded. “Although older women have an increased risk of many pregnancy complications, a higher risk of stroke may not be one of them.” — by Savannah Demko

Disclosures: The researchers report no relevant financial disclosures.