According to the Center for Disease Control In the United States, and the American College of Obstetricians and Gynecologists, one in 33 babies will be born with some form of serious birth defect. A birth defect is an abnormality in the way a newborn's body looks or functions. Birth defects can lead to cognitive, emotional, or physical disabilities, and in some cases, they can be fatal. To understand birth defects, it's key to understand that there are two overarching types structural and functional, or developmental. STRUCTURAL birth defects are those that occur when a specific body part is missing or has formed incorrectly. Both heart defects and spina bifida, a birth defect caused by the incomplete closure of the embryonic neural tube, which results in the spinal cord not being fully formed and covered, are both examples of structural defects. FUNCTIONAL birth defects, meanwhile, refer to problems with the way a body part or system functions. These problems often lead to developmental disabilities. Tay-Sachs disease, which is a fatal disorder of the central nervous system, is an example of a functional birth defect. Of ALL birth defects, the three most common are: heart defects, which affect as many as one in 100 babies in the USA according to the CDC and March of Dimes. Cleft lips and cleft palates, which occur in one in 700 newborns in the United States, according to the CDC and Down syndrome, which affects about one in 733 babies born in the USA, according to the National Down Syndrome Society. Birth defects can be caused by factors relating to the environment, to genetics, or to a combination of the two. One of the most common reasons GENETIC defects occur is that one or more of a baby's 20,000-25,000 genes is missing or flawed. Problems of this nature can be passed to a baby from either-or both-parents. These are called single-gene defects, which are mutations in a single gene, and they include a form of dwarfism, Achondroplasia , which affects about 1 in 15,000 to in 40,000 births, and occurs in all races and in both sexes and the serious lung disorder cystic fibrosis. Genetic birth defects can ALSO arise when something goes wrong with a baby's chromosomes. A healthy human has 23 pairs of chromosomes, or 46 in total. But, if an error occurs during an egg or a sperm cell's development...a baby created from that egg or that sperm can be born with too few, too many, or damaged chromosomes. Down syndrome is an example of a chromosomal birth defect, which occurs when an additional chromosome is added to the 21st pair of chromosomes. Thus, it is aptly called Trisomy 21. While genetic birth defects like these are common, so are ENVIRONMENTAL birth defects. Drinking alcohol during pregnancy is an environmental factor that can lead to the development of some potentially serious defects. Each year between 1,000 and 6,000 babies in the United States are born with fetal alcohol syndrome or FAS, which manifests as a pattern of mental and physical birth defects common in babies of mothers who drink heavily during pregnancy. Other common environmental teratogens, or toxic substances know to affect fetuses, include: certain recreational drugs, like crack and cocaine, and prescription drugs, like Acutane, You must check with your doctor before continuing any prescription drugs you may be taking. And if you have a drug or alcohol problem, talk to your healthcare provider, getting help early is critical for the baby's health! A woman's risk of having a baby with certain birth defects involving chromosomes is also likely to increase with age. Paternal age is also a factor in birth defects. Other environmental birth defects may stem from infections that a woman may contract during pregnancy. A rubella infection, for example, can lead to heart defects, vision and hearing problems, or in more serious cases, mental retardation in a baby. The weeks before and during the first trimester are most dangerous for infection of a fetus with respect to rubella infection. Additionally, a mother's untreated sexually transmitted disease can be passed to a newborn and cause problems. For example, the transmission of genital herpes could lead to brain damage or cerebral palsy in a baby. Sometimes, a birth defect will be multifactorial, arising from a COMBINATION of genetics and environment. In cases like these a baby may inherit a gene that will make him MORE likely to have a birth defect... but ONLY if he is exposed to certain environmental substances, like a virus or cigarette smoke. OR if the mother doesn't get enough folic acid before becoming pregnant in the case of Neural Tube Defects like Spina bifida. As for heart defects, exposure to certain medications during the first trimester of pregnancy may play a role in causing heart defects. Other causes include maternal alcohol abuse, rubella infection, and diabetes during pregnancy." Whatever their cause, birth defects can be confusing, overwhelming, and devastating. So if YOUR child is affected, speak with your doctor about treatment for him and support for you.