Yes.. Ebstein's anomaly can vary in severity. Very mild forms are most of the times inconsequential. Severe forms may cause illness in early infancy, and sometimes require surgical repair. I'm assuming your doctor referred you to a pediatric cardiologist for a fetal echo. Ask about the severity of the ebsteins and the associated tricuspid regurgitation (valve leakage). Good luck.
Complex answer. Ebstein anomaly encompasses a spectrum of problems associated with an abnormal tricuspid valve. The severity of symptoms, clinical course and approach treatment can vary widely, so you need to have a discussion with a pediatric cardiologist and team with experience in dealing with this condition.