Pregnancy drugs, fetal germline epigenome, and risks for next-generation pathology: A call to action.

Drugs taken during pregnancy can affect three generations at once: the gestating woman (F0), her exposed fetus (F1), and the fetal germ cells that confer heritable information for the grandchildren (F2). Unfortunately, despite growing evidence for connections between F0 drug exposures and F2 pathology, current approaches to risk assessment overlook this important dimension of risk. In this commentary, we argue that the unique molecular vulnerabilities of the fetal germline, particularly with regard to global epigenomic reprogramming, combined with empirical evidence for F2 effects of F1 in utero drug and other exposures, should change the way we consider potential long-term consequences of pregnancy drugs and alter toxicology's standard somatic paradigm. Specifically, we (1) suggest that pregnancy drugs common in the postwar decades should be investigated as potential contributors to the "missing heritability" of many pathologies now surging in prevalence; (2) call for inclusion of fetal germline risks in pregnancy drug safety assessment; and (3) highlight the need for intensified research to ascertain generational impacts of diethylstilbestrol, a vanguard question of human germline toxicity. Only by fully addressing this important dimension of transplacental exposure can we responsibly evaluate safety of drug exposures during pregnancy and convey the full scope of risks, while also retrospectively comprehending the generational legacy of recent history's unprecedented glut of evolutionarily novel intrauterine exposures. Environ. Mol. Mutagen. 60:445-454, 2019. © 2019 Wiley Periodicals, Inc.