Objectives Adequate prepregnancy prediction of maternal cardiovascular and offspring risk is important for counselling and management of pregnancy in women with congenital heart disease (CHD). Therefore we performed a study to identify the optimal assessment strategy for estimating the risk of pregnancy in women with CHD.

Methods In this prospective study, we determined the outcomes of 213 pregnancies in 203 women with CHD. The ZAHARA I (Zwangerschap bij Aangeboren HARtAfwijkingen I) and CARPREG (CARdiac disease in PREGnancy) risk scores were calculated for each pregnancy, as was the total number of cardiovascular (TPc) or offspring risk predictors (TPo) from these and other studies combined. Pregnancies were also classified according to the modified WHO classification of maternal cardiovascular risk and according to disease complexity (DC).

Results Maternal cardiovascular events occurred during 22 pregnancies (10.3%). Offspring events occurred during 77 pregnancies in 81 children (37.3%). Cardiovascular and offspring event rates increased with higher risk scores, higher TPc or TPo, higher WHO class and greater DC. The highest area under the curve (AUC) for maternal cardiovascular risk was achieved by the WHO class (AUC: 0.77, p<0.0001). AUC for the ZAHARA I risk score was 0.71 (p=0.001), and for the CARPREG risk score 0.57 (p=0.32). All models performed insufficiently in predicting offspring events (AUC≤0.6).

Conclusions The WHO classification is the best available risk assessment model for estimating cardiovascular risk in pregnant women with CHD. None of the offspring prediction models perform adequately in our cohort.