4 Interspecies differences regarding the teratogenicity of drugs can result from differing pharmacokinetic processes that determine the crucial concentration-time relationships in an embryo. Protein binding in the mother is also an important determinant of placental transfer because only free concentrates in maternal plasma can reach equilibration with the embryo during organogenesis. Extrapolating data from these studies to humans and subsequently publishing supposed effects in the mass media, without a clear understanding of the differences, can cause women and their health professionals unnecessary anxiety. This kind of information sells newspapers but does nothing to inform the public of the real risks or safety of drugs during pregnancy. Over the years, many studies in the literature have selectively reported research results, which ultimately find their way into the mass media.
Papers also document the bias against publication of reassuring studies.
The public should be wary of gaining medical knowledge through newspaper and other media reports. The only way to ascertain the ultimate risk or safety of drugs during pregnancy is to do human studies. Prospective, controlled, epidemiologic studies of the pregnancy outcomes of women who consumed a particular drug during pregnancy is one example. Even this type of research is not ideal because, for obvious ethical reasons, women cannot be enrolled in randomized, controlled studies, and because the limited size of the studies means they do not have the statistical power to detect increased risk of rare malformations. Another example is case-control studies, where drug use among mothers whose babies have a specific malformation is compared with that of mothers whose babies do not.