This paper explores the viewpoints of nineteenth-century Brazilian physicians regarding women’s roles as the ‘propagators of the race’. It emphasises their perspectives on reproduction, breast feeding, and the involvement of enslaved wet nurses in a society grappling with significant paradoxes and conflicts as it sought to embrace modernisation. It also examines various aspects of women’s health and childcare, encompassing topics like miscarriage and puériculture. Through an analysis of medical discourse, this paper underscores physicians’ profound influence in shaping societal assumptions surrounding maternal roles in Brazil. These understandings were instrumental in shaping the expectations for a ‘modern nation’, where racial considerations intertwined with broader discourses about female bodies. Drawing on diverse sources from the latter half of the nineteenth century, including newspapers and medical records, this paper also highlights the lived experiences of mothers—both tangible realities and imagined constructs. It emphasises how these experiences became integrated in ideological debates that centred on maternity, race, nationhood and modernity within a South Atlantic context. Conducting a discourse analysis of published medical sources, the paper finally uncovers the intricate interplay between reproductive politics, biological risk perceptions and national defence. It dissects how these elements coalesced into the language of biopolitics, moulding regulations and institutional control over the bodies of both white and black women. This exploration aims to enrich discussions about the intricate dynamics shaping institutional actions within the realms of reproductive health and national interests.