Elevated Risk of Cerebral Arteriovenous Malformation Rupture during Pregnancy and Puerperium

OBJECTIVE: Cerebral arteriovenous malformations (AVM) pose a significant risk during pregnancy because of hormonal changes and increased hemodynamic stress. This study aims to assess the risk of AVM rupture during pregnancy and puerperium and to identify risk factors associated with rupture. METHODS: This prospective cohort study included 588 women with AVMs and a history of pregnancy, enrolled from a nationwide registry in China between August 2011 and August 2021. A case-crossover design was used to compare rupture risk during pregnancy, puerperium, and non-pregnancy periods, adjusting for clinical and morphological factors. Multivariable logistic regression analysis identified independent risk factors. RESULTS: The risk of AVM rupture was significantly higher during pregnancy compared to non-pregnancy periods (4.5% vs 1.6%; risk ratio [RR], 3.1; 95% confidence interval [CI], 2.3-4.2; p < 0.001). The risk was particularly elevated during the second and third trimesters. Key factors independently associated with increased rupture risk included adolescent or advanced-age pregnancy (adolescent ≤19 years or advanced ≥35 years, odds ratio [OR], 8.32; 95% CI, 2.09-28.12, p = 0.001), a history of AVM rupture before pregnancy (OR, 4.20; 95% CI, 1.37-11.40; p = 0.007), diffuse nidus (OR, 2.32; 95% CI, 1.07-5.12; p = 0.033), and multifetal pregnancy (OR 18.31; 95% CI, 1.14-293.27; p = 0.040). INTERPRETATION: Pregnancy substantially increases the risk of AVM rupture, particularly during the second and third trimesters and compared to pre-first pregnancy periods. Risk factors such as adolescent or advanced-age pregnancy and multifetal pregnancy further increase the risk. These findings underscore the importance of tailored management during pregnancy for optimizing maternal and fetal outcomes. ANN NEUROL 2025;98:1136-1145.