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relative risk
environmental exposures and risk factors

picture of babyWe study exposures that include anything the fetus is exposed to as well as anything that may alter conditions within the womb. Because most structural development of the fetus occurs during early pregnancy, our studies usually focus on this "periconceptional" period—the month before and first 3 months after conception. conception.
bullet Exposuresanything that comes into
direct contact with the mother or fetusstudied because they may have a cause-and-effect link with birth defects.
bullet Risk factorssuch as social or economic conditionsmay provide clues that can help pinpoint causes. For example, educated women may be more likely to take multivitamins, lowering the risk for certain birth defects.


The type of studies conducted by the California Birth Defects Monitoring Program cannot provide a yes or no answer about whether an exposure causes birth defects. Instead, results are reported as changes in birth defects risk for exposed pregnancies compared to unexposed.

bullet Higher risksa doubling or moresuggest an association between the exposure and the condition in question. This may mean the studied exposure (or a closely related exposure or factor) contributes to the birth defect.
bullet Decreased risksone half or lessindicate a protective effect. In other words, the exposure appears to prevent the birth defect from occurring.
bullet No change in risk implies the exposure and the defect are not closely related.

Many other factors can influence results, however. For this reason, additional studies are always needed to confirm and clarify research findings.

research findings

The California Birth Defects Monitoring Program has completed many studies on a variety of birth defects, looking at a wide range of environmental exposures and risk factors in both the mother and father. Additional information is available on these topics:

Air pollution
Chemicals and solvents
Diet and nutrition
Drinking water
Electromagnetic fields
Folic acid/vitamins
Gene-environment interactions
Hazardous waste sites
Illness/ infections
Obesity and body mass
Prenatal care/pregnancy
Social/economic factors
Stressful life events

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