Abstract： Background:Right dominant heart (RDH) in fetuses can occur with a number of cardiac as well as noncardiac anomalies.Analysis of the enlargement of the right cardiac chamber in the fetus remains a major challenge for sonographers and echocardiographers.The aim of this study was to report the experience with prenatal diagnosis of RDH in the fetuses over a 7-year period.Methods:Fetuses with prenatal diagnosis of RDH from July 2009 to July 2016 were evaluated in two different categories:according to thegestational age,Group Ⅰ (n =154,second trimester) and Group Ⅱ (n =298,third trimester);and according to the fetal echocardiography diagnosis,Group A (n =452,abnormal cardiac structure) and Group B (n =90,normal cardiac structure).Differences in categorical variables were assessed by Chi-square exact test and continuous variables were evaluated by independent Student's t-test or Mann-Whitney U-test depending on parametric or nonparametric nature of the data.Results:Over a 7-year period,452 fetuses were referred for the assessment of suspected RDH.Left-sided obstructive lesions were observed most frequently in the fetuses with RDH.When comparing Group Ⅰ with Group Ⅱ and Group A with Group B,the latter groups exhibited significant differences in the right/left ventricle (RV/LV) ratio (1.435 vs.1.236,P =0.002;1.309 vs.1.168,P =0.047),RV width Z-score (1.626 vs.1.104,P ＜ 0.001;1.553 vs.0.814,P =0.014),and above +2 cutoff percentages (14.3％ vs.22.5％;P =0.038;21.5％ vs.12.2％,P =0.046).Multivariable logistic regression revealed no variables associated with perinatal survival.Conclusions:The study demonstrates that RDH warrants careful attention to the possible presence of a structural cardiac anomaly,especially left-sided obstructive lesions.A diagnosis of RDH is best supported by a combination of the RV Z-score and RV/LV ratio.Most of the fetuses with RDH and structurally normal hearts had favorable outcomes.