###Human: Is it possible for a 3 mm hole in baby's heart to close by itself? ###Assistant: Hi. Yes, your doctor has said right (attachment removed to protect patient identity). Usually ventricular septal defects, especially if small and muscular, close on itself over time. If there are no symptoms like turning blue or black, difficulty in breathing, recurrent chest infections, there is nothing to worry. Just wait and watch. Do echo every year to see the progress. You can consult me with echocardiography report to guide you further.