Objective To measure cardiovascular outcomes and risk associated with pregnancy among women diagnosed with rheumatic heart disease (RHD) prior to 20 weeks’ gestation. Design Retrospective cohort study using linked RHD register, midwives, hospital and death records. Setting Population-level analysis of all births to women with RHD in four Australian jurisdictions (covering 71% total / 88% Indigenous population). Sample Females aged 12-44 years with first RHD diagnosis prior to age 35 years with at least one birth record, 2002-2017. Methods Survival methods (incorporating mixed effects and time-varying covariates) estimated proportions and Hazard Ratios. Main Outcome Measures Probability of hospitalisation for new Cardiovascular complications including pulmonary hypertension secondary to left heart disease, heart failure, valvular surgery, stroke, infective endocarditis, atrial fibrillation, acute pulmonary oedema, cardiomyopathy and/or death. Results We identified 558 pregnancies in women with uncomplicated RHD (345 women) and 88 pregnancies in women with complicated RHD (60 women). During pregnancy 4.5% of women with uncomplicated RHD and 31.8% of women with complicated RHD experienced new cardiovascular complications. Cardiovascular complication risk was 3 to 6-fold higher during pregnancy than non-pregnancy and did not differ by RHD stage. Conclusions Women with RHD experienced heightened cardiovascular complication risks during pregnancy in alignment with RHD stage at 20 weeks gestation.