ObjectiveThis study aims to compare different references for the fetal risk of drugs used in pregnancy to provide evidence for the safety of drug use in pregnancy.MethodsFour drug databases, including Lexicomp, Micromedex, TERIS, and Reprotox, as well as two books of drugs in pregnancy edited by Briggs and Schaefer, were searched. Descriptive analysis was performed regarding the definition of pregnancy recommendations and the specific content of medication.ResultsThe six references employed slightly different approaches to drugs in pregnancy, however, all of them included summaries of the risk in pregnancy, data of crossing the placenta, and human and animal data. The databases of Micromedex, TERIS, and a book edited by Briggs had their risk classification systems for drug use during pregnancy. For specific drugs, the summary of different information in pregnancy was different, the amount and content of listed evidence varied, and there was no evaluation of the quality and relevance of evidence among the references.ConclusionsThere is no consensus on the risk assessment of drugs in pregnancy. Risk classification systems for drugs in pregnancy are still an important method for determining the fetal risk of drugs. The existing references merely list studies of drugs in pregnancy, without comprehensive quality assessment. A methodological study of assessment of the risk of drugs in pregnancy is required.