Fetal ventricular septal defect of three millimeters at 26 weeks of gestation requires cardiac ultrasound to rule out the combination of other cardiac malformations. If the ventricular septal defect is not further enlarged and is not combined with cardiac malformations, you can wait for it to heal on its own, but if it persists in enlargement, surgical intervention is needed. Fetal ventricular septal defect is one of the congenital heart diseases. Small ventricular septal defects are not serious, while larger ventricular septal defects can affect heart function. A three-millimeter fetal septal defect at 26 weeks of gestation is not large and may be able to grow closed between one and one-and-a-half weeks of age. Regular obstetric ultrasound review is needed to continuously monitor the ventricular septal defect, and fetal cardiac ultrasonography is performed when necessary to check for abnormalities in cardiac function. Most ventricular septal defects will heal on their own if not combined with other cardiac anomalies. Some require surgery after birth, and the prognosis is generally good. During pregnancy, you should pay attention to rest more, at the same time, you should relax, avoid tension, anxiety, any discomfort should go to the hospital in a timely manner, by the doctor to clarify the diagnosis, and cooperate with the doctor to deal with the symptoms.