Birth Defects

After being in the womb for months and in the birth canal for hours, most newborns show effects that may be frightening to new parents, even raising the fear of birth defects. Heads may be misshapen, and one or both ears may be folded over or sticking out. Skin may be red, showing signs of forceps use, or yellow, indicating jaundice. In most cases, neither condition is serious. Babies may be placed under lights to correct jaundice, and redness clears up on its own. Thirty percent of all newborns have facial acne, and many have drooling rash. Half of all infants have erythema toxicin, a rash that looks like insect bites. It normally disappears within a month. Eyelids and breasts may be swollen. In some infants tear ducts are blocked, but in 90 percent of cases, the condition clears up without treatment by the end of the first year. In healthy newborns, the body soon takes on a normal appearance. In babies born with birth defects, abnormalities do not disappear, even though they may not be evident for some time, as in the case of autism spectrum disorders (ASD) or Huntington's disease.

Birth defects are the leading cause of infant death. Defects may be structural, functional, metabolic, behavioral, or hereditary, manifesting as physical or mental abnormalities, or both. The most widely used classification of birth defects is the International Classification of Diseases. Teratology is the branch of science that conducts research on the causes, mechanisms, and patterns of abnormal fetal development. [Page 251]Approximately eight million babies around the world are born each year with some kind of genetic birth defect. Low-weight babies, even if they are fullterm, are particularly vulnerable to a number of defects. A 2006 report by the March of Dimes Foundation contends that in 70 percent of all cases, birth defects could have been prevented or mitigated. Underlying causes associated with genetic birth defects in developing countries include high incidences of babies born to older women, inbreeding, and poor nutrition.

Without treatment, around 3.3 million children die from birth defects before the age of 5, and another 3.2 million live with chronic disabilities. In a number of cases, birth defects are associated with an increased risk of sudden infant death syndrome (SIDS). More than 94 percent of all birth defect–related deaths occur in middle and lower income countries. The highest rate of genetic birth defects is found in the Sudan (82 per 1,000 live births) and the lowest rate in France (39.7). The United States falls between those extremes at 47.8. The most common causes of genetic birth defects in the March of Dimes study were congenital rubella, congenital syphilis, iodine deficiency, and fetal alcohol syndrome. Many birth defects are congenital rather than genetic, occurring during fetal development. The five most common causes of congenital birth defects, comprising more than a fourth of the total, include congenital heart defects, neural tube defects, thalassemia and sickle cell disease, Down syndrome, and enzyme disorders. Infants born to two parents from countries that lie in the “malaria belt” are at particular risk for developing thalassemia and sickle cell disease. An enzyme disorder, Tay-Sachs is a recessive, single-gene disorder that involves the inability to break down fatty deposits in brain and nerve cells. It is most common in Jews of eastern European descent. The disorder may not be evident for the first six months of life. Symptoms include behavior changes, paralyses, and blindness. Without treatment, death usually occurs between the ages of 3 and 4.

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