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One of the goals of birth defects research is to better understand risk or preventive factors for birth defects so that strategies for prevention can be developed. In this article, we have selected four areas of birth defects research that have led to the development of prevention strategies. These areas include rubella virus as a cause of congenital rubella syndrome, folic acid as a preventive factor for neural tube defects, cytomegalovirus infection as a cause of birth defects and developmental disabilities, and alcohol as a cause of fetal alcohol spectrum disorders. For each of these areas, we review key clinical and research findings that led to the identification of the risk or preventive factor, milestones in the development of prevention strategies, and the progress made thus far toward prevention.

Background: Teratology studies must be carefully designed to minimize potential secondary effects of vehicle and delivery routes. A systematic method to evaluate chick models of early embryogenesis is lacking., Methods: We investigated 3 experimental approaches that are popular for studies of early avian development, in terms of their utility for teratogen assessment starting at gastrulation. These included in vitro embryo culture, egg windowing followed by direct application of a carrier vehicle to the embryo, and injection of a carrier vehicle into the egg yolk. We also developed a morphologically based scoring system to assess development of the early embryo., Results: The in vitro culture and egg windowing approaches both caused an unacceptably high incidence of central nervous system and cardiac abnormalities in vehicle-treated embryos, which made it difficult to identify teratogen-specific defects. In contrast, exposing chick embryos to vehicle via direct egg yolk injection did not induce developmental anomalies., Conclusions: Optimization of the exposure route of potential toxicants to the embryo is critical because control treatments can cause developmental anomalies. In ovo yolk injection minimizes perturbation of young embryos and may be appropriate for teratogen delivery., (Copyright (c) 2005 Wiley-Liss, Inc.)