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the problem with birth defects
facts and figures
economic impact
infant mortality
whos at risk
causes unknown

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causes remain a mystery

Despite recent advances in genetic research, we cannot pinpoint the causes of most birth defects. Evidence suggests the need for careful study to untangle the complex interplay of factors involved.

bullet Some birth defectsfewer than 10%-result from known prenatal exposures. German measles, diabetes or heavy drinking during pregnancy are all examples of teratogens, exposures that can cause birth defects.
bullet Others are due to abnormal genes or chromosomes. These may be inherited or represent new mutations.
bullet Most birth defectsincluding common conditions like neural tube and heart defectsarise from interactions between genes and non-genetic factors. For instance, we discovered that smoking increases risk for oral clefts, particularly in babies who inherit a specific gene variant.


bullet Research findings in animals often don't apply to humans.
bullet Despite the progress of the Human Genome Project, we don't understand the purpose and function of most genes.
bullet Exposures during pregnancy are difficult to identify and document. Multiple risk factors may be present.
bullet Many common, everyday exposures have not been well studied. Environmental issueslike air and water pollutionare sources of particular public concern.

Finding birth defects causes depends on rigorous study of gene-environment interactions in humansthe main focus of the California Birth Defects Monitoring Program.

unanswered questions

picture of mother with childSonia did everything right. While pregnant, she followed her doctor's instructions, didn't use alcohol or drugs, ate nutritious meals and exercised regularlylong walks around the commercial flower fields near her San Diego home.

When Sonia's son was born with a life-threatening heart defect, the daily walks haunted her. Had pesticides sprayed over the fields harmed her developing child? Medical science did not have the answer. The causes of her child's heart abnormalitylike the majority of birth defectsare not well understood. Most potential environmental exposures, including pesticides, were not well-studied in human pregnancy.

Sonia's storya composite of manyis not unusual...1 in every 33 babies is born with birth defects. Many are fatal or will cause lifelong handicapchildren who may never see, hear or walk. And yet, the causes of birth defects remain largely a mystery.

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