Denman studied medicine at St. George's Hospital in London, and also attended William Smellie's lectures on midwifery, before serving as a naval surgeon. Between 1769 and 1783 he worked as an obstetrician in the Middlesex Hospital. On William Hunter's death in 1783 he became the leading obstetrician in the capital, where he established a large private practice. Denman is remembered for introducing the practice of induced labour in instances where the mother's life was imperilled. Denman's most important publication was his An introduction to the practice of midwifery, an extremely popular work that reached a fifth edition by 1805, and a seventh edition by 1832. His Collection of engravings, which is accompanied by a text in English and French, includes fifteen plates drawn by J. van Rymsdyk, R. Livesey, F. Burnie, R. Atkinson, F.P. Nodder, and G. Porter; they were engraved by Miller, C. Knight, W. Skelton, and T. Medland. Eight more plates were added to the third edition of An introduction to the practice of midwifery in 1801. Denman's other published writings include Essays on puerperal fever (1768), and Aphorisms on the application and use of the forceps and vectis in preternatural labours (1783).