We 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.
|Exposures—anything that comes into
direct contact with the mother or fetus—studied because they may have a cause-and-effect link with birth defects.
|Risk factors—such as social or economic conditions—may 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.
|Higher risks—a doubling or more—suggest 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.|
|Decreased risks—one half or less—indicate a protective effect. In other words, the exposure appears to prevent the birth defect from occurring.|
|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.