PPT Slide
Notes:
It is worth noting that these teratogenic effects were all recognized after “natural experiments”. A cluster of birth defects occurred unexpectedly in domesticated animals, and scientific research traced the cause to the mother’s consumption of a particular plant during pregnancy. Ingestion of these substances was not known to pose a hazard to pregnant animals before the “epidemic” of birth defects was observed.
Some dietary supplements are safe or even beneficial for use in pregnancy. The outstanding example is supplemental folic acid, which has been shown by rigorous scientific study to reduce the risk of neural tube defects in the offspring. However, the apparent safety of other dietary supplements may be because they simply have not been adequately studied. One certainly cannot assume that there is no effect just because there has not been adequate study of a substance in pregnancy.