# Mode of Birth and Stroke Risk After Childbirth Among Women With Moyamoya Disease

## TL;DR

A study of over 1,600 women with moyamoya disease found no significant difference in stroke risk after childbirth based on whether they had a cesarean or vaginal birth.

## Contribution

The study provides large-scale evidence that mode of birth may not need to be routinely dictated for women with moyamoya disease.

## Key findings

- No significant difference in stroke risk was found between cesarean and vaginal births in women with moyamoya disease.
- The effect of birth mode on stroke risk was modified by the patient’s clinical onset type (e.g., hemorrhagic, ischemic).
- Stroke incidence was highest in the early postpartum period (≤6 months) and decreased over time.

## Abstract

Is the mode of birth (cesarean vs vaginal) associated with differences in the risk of postpartum stroke among women with moyamoya disease?

In this cohort study of 1683 women with moyamoya disease, the overall risk of postpartum stroke did not significantly differ by mode of birth. However, the effect of the mode of birth was significantly modified by the patient’s clinical onset type (eg, hemorrhagic, ischemic, or asymptomatic or nonvascular).

These findings suggest that a routine preference for cesarean birth among women with moyamoya disease may be unnecessary.

There is limited large-scale evidence to guide the optimal mode of birth for patients with moyamoya disease (MMD).

To evaluate whether the mode of birth (cesarean vs vaginal) is associated with stroke risk after childbirth for women with MMD.

This cohort study evaluated stroke outcomes up to 3 years after childbirth. A nationwide, population-based analysis was performed using data from the Health Insurance Review and Assessment Service of South Korea. Individuals with MMD from January 1, 2002, to December 31, 2023 were identified. Among 31 750 patients, those with birth-related procedure codes were selected. The study population was restricted to women aged 19 to 49 years, and those with a diagnosis of malignant neoplasm within 3 years before the index date (date of childbirth) were excluded. Data were analyzed from June 11 to September 8, 2025.

Mode of birth.

The primary outcome was any stroke, defined as a composite of ischemic or hemorrhagic stroke. Secondary outcomes included ischemic stroke, hemorrhagic stroke, and transient ischemic attack.

Of 1683 women analyzed (mean [SD] age, 33.6 [7.8] years), 1077 (64.0%) had cesarean births, and 606 (36.0%) had vaginal births. Post partum (3 months), any stroke incidence was 63.49 and 33.33 per 1000 person-years for cesarean and vaginal births, respectively. Multivariable analyses showed no significant risk differences for any stroke by birth mode at 3 months (adjusted hazard ratio [aHR], 0.71 [95% CI, 0.26-1.97]; P = .52) or 3 years (aHR, 0.90 [95% CI, 0.55-1.47]; P = .67). A significant interaction was observed between the mode of birth and the clinical onset type of MMD for the risk of any stroke (interaction P = .04 after Bonferroni correction); the adjusted HR for vaginal vs cesarean birth was 0.10 (95% CI, 0.01-0.79) in the asymptomatic or nonvascular onset subgroup, 1.49 (95% CI, 0.73-3.03) in the ischemic onset subgroup, and 0.94 (95% CI, 0.50-1.77) in the hemorrhagic onset subgroup. Notably, stroke incidence peaked in the early postpartum period (≤6 months: 35.7 per 1000 person-years), decreased at 1 year, and thereafter remained at a similar level.

In this cohort study of women with MMD, MMD itself was not found to be an absolute indication for cesarean birth; birth planning should be individualized based on obstetric factors and clinical onset type rather than routine preference for cesarean birth. In addition, vigilant monitoring and preventive strategies during the early postpartum period are warranted.

This cohort study evaluates whether the mode of birth (cesarean vs vaginal) is associated with stroke risk after childbirth among women with moyamoya disease using data from the Health Insurance Review and Assessment Service of South Korea from 2002 to 2023.