Background: Publication track record can impact careers of researchers. Therefore, monitoring gender representation in medical research is required to achieve equity in academia. Methods: We gathered bibliometric data on original research articles published between 2010 and 2019 in The New England Journal of Medicine, Nature Medicine, Journal of the American Medical Association, The BMJ, and The Lancet using the Web of Science indexing database. We associated publication and citation frequency with author gender, count, and institute affiliation, and research keywords. Findings: We analyzed 10,558 articles and found that women published and were cited less than men. There were fewer women as senior (24.8%) than leading authors (34.5%, p<0.001). The proportion of female authors varied by country with 9.1% last authors from Austria, 0.9% from Japan, and 0.0% from South Korea. The gender gap decreased longitudinally and faster for last (-24.0 articles/year, p<0.001) than first authors (-14.5 articles/year, p=0.024). The trend varied by country and even increased in China and Israel. Author count was associated with higher citation count (R 0.46, p<0.001) as well as with male first (n=11 vs. n=10, p<0.001) and last authors (n=11 vs. n=10, p<0.001). We also discovered that usage of research keywords varied by gender, and it partly accounted for the difference in citation counts by gender. Interpretation: Gender representation has increased both at the leading and senior author levels although with country-specific variability. The study frame can be easily applied to any journal and time period to monitor changes in gender representation in science.

O.B. declares no Competing Non-Financial Interests but the following Competing Financial Interests: consultancy fees from Novartis, Sanofi, and Amgen, outside the submitted work.

This study was supported by research grants from the Helsinki University Hospital.

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Codes and a 100-row data example are available at https://github.com/obruck/International-Research-Impact. Raw data can be downloaded from Clarivate Web of Science, with instructions provided in the Github repository.