Clinical trials in pregnancy and the "shadows of thalidomide": Revisiting the legacy of Frances Kelsey

Despite great need for improved understanding of the use of drugs and biological products in pregnancy, clinical trials in pregnancy are rare, therapeutics in pregnancy are woefully understudied, and pregnant individuals are routinely excluded as trial participants. Recently, however, the U.S. Food and Drug Administration (FDA) has signaled strong support for advancing scientific research with pregnant populations, marking a significant shift from the past. Over the last sixty years, precaution and fear have largely characterized clinical research in pregnancy, deriving in large part from a protectionist ethic that materialized after the thalidomide drug disaster. FDA reviewer Frances Kelsey courageously prevented thalidomide from being marketed in the United States, and her work guided and solidified the FDA's image as protector of the general population from unsafe and ineffective drugs. Yet, when it comes to protection, pregnant persons have been left behind, and experts refer to the "shadows of thalidomide" that hamper clinical trials in pregnancy. Drawing on analysis of Frances Kelsey's archived papers in addition to focused media coverage of Kelsey and thalidomide, we discuss the durable cultural narrative surrounding Kelsey's important work. We argue that revisiting Kelsey's legacy with attention to themes that have characterized her achievement-staying vigilant, prioritizing safety, and mitigating pharmaceutical-based harm-in fact facilitates progress toward the ethical obligation to protect pregnant people through research, toward the generation of pregnancy-specific data for evidence-based care, and toward realizing Kelsey's legacy of safeguarding pregnant people and their offspring from the harms of untested drugs.