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How Your Actions Affect Your Baby's Development |
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4 Week -
Pregnancy
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How Your Actions Affect Your Baby's Development
During pregnancy, nearly all parents worry whether their baby will be perfect. Most parents worry unnecessarily. Major birth defects are apparent in only about 3% of all newborns at birth. Of those 3%, are causes of these abnormalities known? Could they have been prevented?
Abnormal Fetal Development
Teratology is the study of abnormal fetal development. An exact cause or reason for a birth defect is found in less than half of all cases. Obstetricians and other doctors providing care to pregnant women are often asked about substances (teratogens) that may be harmful. Researchers have been unable to prove the danger of some agents we believe are harmful. They have proved the harm of other agents.
Some agents cause major defects if exposure occurs at a specific, critical time in fetal development. But they may not be harmful at other times. Once the fetus has completed major development, usually by the 13th week pregnancy, the effect of a certain substance may be only growth retardation or smaller organ size rather than large structural defects. One example is rubella. It can cause many anatomical defects, such as heart malformations, if the fetus is infected during the first trimester of pregnancy. A rubella infection occurring later is less serious.
Individual Response to Exposure
Individual responses to particular agents and to different doses of agents vary greatly. Alcohol is a good example. Large amounts appear to have no effect on some fetuses, while other fetuses may be harmed by low amounts.
Animal studies provide much of our information about possible harmful agents. This information can be helpful but cannot always be applied directly to humans. Other information comes from situations in which women were exposed who did not know they were pregnant or that a particular substance could be harmful. Information gathered from these instances is difficult to apply directly to a particular pregnancy.
A list of known teratogens and the effects they may have on an embryo or fetus appears on page 61. If you have taken any of these substances, discuss them as soon as possible with your healthcare provider for your peace of mind. If testing or follow-up is necessary, your doctor will advise you.
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