Adverse pregnancy outcomes and long-term risk of cardiac arrhythmias and conduction disorders: a nationwide cohort study

Introduction Adverse pregnancy outcomes (APOs) are established markers of future cardiovascular disease, yet their association with cardiac arrhythmias and conduction disorders remains insufficiently characterized. APOs may confer arrhythmogenic vulnerability through inflammation, accelerated atherosclerosis, persistent myocardial remodeling, and autonomic dysregulation. Purpose To examine how APOs are associated to the short- and long-term risk of cardiac arrhythmias and conduction disorders, overall and by subtype, among primiparous women. Methods In this nationwide population-based cohort study, we included all primiparous women (median age 28 [IQR 24-32]) with singleton births registered in the Swedish Medical Birth Register between 1992 and 2019, without prior cardiovascular disease (n 1 213 474). Women with ≥1 APO (hypertensive disorder of pregnancy, preterm birth, fetal growth restriction, placental abruption, or stillbirth) (n 164 831) were compared with women without APOs (n 1 048 643). The primary outcome was a composite of cardiac arrhythmias and conduction disorders identified through national registers. Secondary analyses evaluated arrhythmia subtypes (atrial fibrillation/flutter, supraventricular tachycardia, ventricular arrhythmia, and conduction disorders). Participants were followed from delivery until incident event, death, emigration, or 31 December 2021. Hazard ratios (HRs) were estimated using Cox proportional hazard regression, adjusted for maternal age, smoking, body mass index, education, in vitro fertilization, and pre-pregnancy diabetes or renal disease. Analyses were stratified by specific APOs. Results During a median follow-up of 14 years, 1 221 primary events occurred among women with APOs and 6 406 among comparators, corresponding to incidence rates of 5.2 versus 4.2 per 10 000 person-years, respectively. APOs were associated with a moderately increased risk of the composite outcome of cardiac arrhythmias and conduction disorders (HRadj 1.22, 95% CI 1.13-1.30), with a higher risk estimate the first year postpartum (HRadj 1.55, 95% CI 1.28-1.63). Stratifying exposure into specific APOs with highest prevalence, showed that HR was highest in women with pregnancy-induced hypertensive disorder (HRadj 1.29, 95% CI 1.17-1.43), followed by preterm birth (HRadj1.23, 95% CI 1.13-1.36), and fetal growth restriction (HRadj 1.18, 95% CI 1.04-1.34). Associations for specific subtypes were directionally consistent but did not reach statistical significance, likely reflecting limited statistical power for less common outcomes. Conclusions In this large nationwide cohort, APOs were associated with a modest but consistent increase in the short- and long-term risk of the composite of cardiac arrhythmias and conduction disorders. These findings support the concept that APOs may confer arrhythmogenic vulnerability and underscore the importance of long-term cardiovascular surveillance in affected women.