You have mentioned all the main causes of a congenital heart defect. Number 1 and 5 can't be modified but rest is can be.

• Every pregnant mother must stop smoking, preferring before getting pregnant and keep avoiding the whole pregnancy period
• Avoid radiation exposure. Tell your doctor that you are carrying a baby so that doctor won't suggest X-ray or CT scan or another test with radiation exposure. If a Radiology technician is a lady, she must wear protectors.
• All teratogenic drugs must be avoided. Consult with a doctor if you are taking any such medicine already, before getting pregnant.

There is a different kind of heart leakage. Some are potentially lethal and the child won't survive. Others can be repaired.
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