I would like to submit our manuscript entitled “Pregnancy drug use in Beijing district during 2016-2018: an analysis of data from Beijing Prescription Evaluation System” for publication inBRITISH JOURNAL OF CLINICAL PHARMACOLOGY.We performed an analysis of prescriptions during pregnancy from Beijing Prescription Comment System from 2016 to 2018. We extracted prescriptions with key words from the system, and screened with specific criteria, in order to summarize and evaluate the patterns and risk factors associated to drugs during pregnancy. Ultimately, we included 647 varieties of chemical or biomedical drugs with 112,566 prescriptions. We performed data processing and statistical analyzes using SPSS 22.0 and Graphpad 8.0 software. Characteristics of prescriptions were evaluated through gestational age, gestational week, prescribing year, prescribing departments. Potential risk of drugs was assessed with FDA categorization, with pareto charts of the drugs or departments. We also carried out multiple logistic regression to explore the risk factors associated to drugs of C, D/X, N/A categories. Finally, drug risk re-classification was performed with Briggs categorization of medicine in B, C, D, N/A categories. The paper described above is original work and has not been published elsewhere, in whole or in part. None of the authors have any conflicts of interests to report. We greatly appreciate your time to review our manuscript and we look forward to hearing from you in due course. Yours sincerely, DU Boran Corresponding author FENG Xin Email: fengxin1115@126.com