Can birth defects be prevented?

Yes: Some can, but not all. Taking Folic Acid supplements before conception can prevent spinal cord defects. Excellent sugar control for a diabetic, avoiding certain drugs or medications early in pregnancy, and being aware of higher risks with advancing maternal age are all important.

Most can.: Most serious birth defects involving the heart and spine/brain can be prevented in 75-90% of cases when Folic Acid is taken daily at 1-5 mg for at least 3-12 months before conception. Avoiding known teratogens (alcohol, valproic acid, vitamin a/retinoic acid, statins, uncontrolled diabetes mellitus, radiation, heat, ace-inhibitors, etc.) can obviously also help prevent serious birth defects.

Some can, some can't: A host of malformations are the result of genetic effects, sometimes single-gene abnormalities, sometimes multifactorial, the result of interaction of genes and environmental factors. The cause of many we haven't a clue. Prevention of genetic defects cam be attempted by having a preconception screening for ethnic-related disorders, and prenatal testing to see if the fetus is at increased risk.