Inclusion Criteria:  All pregnant women (excluding abortion, nonfirst delivery, multiple births) were eligible for inclusion in the present analysis. Cardiac disease of pregnant woman in the analysis mainly included valvular heart disease (VHD), cardiomyopathy, adult congenital heart disease (ACHD), pulmonary hypertension (PH) and other cardiac conditions (primary arrythmia, coronary heart disease, anemic heart disease, hyperthyroid heart disease and others). Only singleton records with a unique medical identified number were used in our analysis. Records with the same date of birth, admission date, discharge date, and facility name were considered as pure duplications, and only one of such records was kept.  Exclusion Criteria:  abortion, nonfirst delivery, multiple births Patients aged <18 years and those with missing information including unique patient identifiers were excluded.