This study analyzes 675,135 doctoral theses from US Ph.D. graduates (1950-2016) across five scientific domains to examine gender disparities in interdisciplinary research (IDR). A novel indicator measures interdisciplinarity using subject co-occurrence matrices from the ProQuest database. Results reveal a growing trend in interdisciplinary theses, yet persistent gender disparities remain, with male-authored theses showing higher interdisciplinarity. Female advisors may exacerbate these disparities. The findings highlight the underrepresentation of women in IDR and suggest policy implications for advancing their careers.

Meijun Liu, Sijie Yang, Yi Bu, Ning Zhang