children s health issues
Overview of Birth Defects
Causes of and Risk Factors for Birth Defects
It is not surprising that birth defects are fairly common, considering the complexities involved in the development of a single fertilized egg into the millions of specialized cells that constitute a human being. Although the cause of most birth defects is unknown, certain genetic and environmental factors increase the chance of birth defects developing. These factors include exposure to Radiation and children , certain drugs (see table Some risks are avoidable. Others occur no matter how strictly a pregnant woman adheres to healthful living practices. Many birth defects develop before a woman knows she is pregnant. A teratogen is any substance that can cause or increase the chance of a birth defect. Teratogens include Radiation and children (including x-rays) Certain Some Drugs That Can Cause Problems During Pregnancy* None Toxins (including alcohol) Most pregnant women who are exposed to teratogens have newborns without abnormalities. Whether a birth defect occurs depends on when, how much, and how long the pregnant woman was exposed to the teratogen (see Exposures During Pregnancy ). Exposure to a teratogen most commonly affects the fetal organ that is developing most rapidly at the time of exposure. For example, exposure to a teratogen during the time that certain parts of the brain are developing is more likely to cause a defect in those areas than exposure before or after this critical period. Keeping a fetus healthy requires maintaining a Diet and weight . For example, insufficient Obesity in the mother also increases the risk of a neural tube defect. Chromosomes and However, many birth defects are caused by new chromosome abnormalities or gene mutations that arise in the fertilized egg and were not inherited from the parents. Birth defects caused by genetic factors often include more than just an obvious malformation of a single body part. Certain infections in pregnant women can cause birth defects (see Infections During Pregnancy ). Whether an infection causes a birth defect depends on the age of the fetus at the time of the exposure to the infection. The infections that most often cause birth defects are Chickenpox (varicella) Cytomegalovirus (CMV) Infection None Erythema Infectiosum (Parvovirus B19 Infection) (parvovirus B19 infection, fifth disease) Herpes Simplex Virus (HSV) Infections None Rubella (German measles) Syphilis None Toxoplasmosis (which can be transmitted in cat litter) A woman can have one of these infections and not know it because some of these infections can cause few or no symptoms in adults. 