Abstract Body (Do not enter title and authors here):
Background
Cardiovascular disease (CVD) remains a leading cause of maternal mortality in the United States, comprising 26.5% of pregnancy-related deaths.

Objective
We aim to evaluate trends in CVD during pregnancy and maternal, obstetric, and fetal outcomes in pregnant women with CVD in the Kaiser Permanente Northern California (KPNC) integrated healthcare system.

Methods
This is a retrospective cohort study of adult KPNC members with moderate or greater valvular heart disease, cardiomyopathy, congenital heart disease, or ischemic heart disease during pregnancy from 2010-2021. Bivariate analyses and multivariable logistic regression were used to evaluate associations between demographic and clinical risk factors and maternal outcomes in pregnant patients with CVD.

Results
Of 320,902 pregnancies, 763 (0.24%) were identified with clinically significant CVD. The prevalence of CVD increased from 0.19% to 0.24% over the decade, predominantly due to an increase in prevalence of women with congenital heart disease. Mean gestational age at delivery was 36.7 weeks with 19.5% experiencing preterm delivery. Cesarean section, pre-eclampsia or eclampsia, and postpartum hemorrhage rates were 29.5%, 20.8%, and 13.1%, respectively. Fetal loss beyond the first trimester occurred in 7.1% pregnancies.
Adverse maternal cardiac outcomes occurred in 12.6% of patients with clinically significant CVD, with the most common outcome being hospitalizations for congestive heart failure. Age, diabetes, parity, BMI, prior heart failure, prior CVD, lower LVEF, and systemic valvular regurgitation were significant predictors of adverse maternal events.

Conclusions
The incidence of CVD during pregnancy increased between 2010-2021, largely driven by an increase in pregnancies among women with congenital heart disease. Rates of adverse maternal cardiac outcomes, pregnancy loss greater than 20 weeks, and maternal mortality in this cohort were similar to those previously reported in other large registries. High rates of pre-eclampsia or eclampsia and postpartum hemorrhage were noted in this cohort. Understanding risk factors for adverse outcomes in a contemporary, diverse setting can help refine cardio-obstetric risk assessment and preconception counseling.