How can the history of birth weight add to our knowledge of women’s living conditions in the past? In this study of newborn weight and economic growth in Boston, Dublin, Edinburgh, Montreal, and Vienna between 1850 and 1930, W. Peter Ward explores the relation between infant size, economic development, and living standards of working-class women in the industrializing West. Drawing on clinical records from urban maternity hospitals and outpatient services, Ward compares birth weight between cities and traces changes in foetal size during a period in which some cities experienced dramatic economic development while others stagnated. Because foetal growth is strongly affected by maternal nutrition, Ward’s research sheds light on the well-being of working-class women whose living conditions have long been obscure and exceedingly difficult to examine.