Maternal mortality was the second-leading cause of death for women in childbearing years up
until the mid-1930s in the United States. For each death, twenty times as many mothers were
estimated to suffer pregnancy-related conditions, often leading to severe and prolonged
disablement. Poor maternal health made it particularly hard for mothers to engage in market
work. Between 1930 and 1960, there was a remarkable reduction in maternal mortality and
morbidity, thanks to medical advances. We argue that these medical advances, by enabling
women to reconcile work and motherhood, were essential for the joint rise in married women’s
labor force participation and fertility over this period. We also show that the diffusion of infant
formula played an important auxiliary role.