Birth defects are categorized as metabolic/biochemical defects, structural/anatomical defects, or chromosomal birth defects that are present from birth. Birth defects impact the way a fetus’s organs or body parts are formed, the way they function, or how the fetus’s body converts or breaks down food into energy (metabolism). As with many disorders, some birth defects are mild and require no or very limited intervention. Other birth defects are considered more serious and require extensive care or require medical or surgical treatment. There are over 4,000 different kinds of birth defects. Recent prevalence rates have found that 1 out of 33 infants born each year, or approximately 3% of all births, in the United States will have a birth defect. This entry discusses the prevalence and ...