The over-reliance on incarceration in the USA is a racialized phenomenon which has affected millions of families - disproportionately people of colour - reconfiguring kinship around the criminal legal system. Mass incarceration, then, disrupts conventional modes of reproduction and threatens reproductive justice, separates families and funnels children into foster care, diverts funds from social services into prisons, restricts women's access to abortion and adequate pregnancy care, shackles women in childbirth, and incarcerates people during their prime reproductive years. Beyond these obvious disruptions to reproduction, incarceration also cultivates certain ways of being a parent. Much of the critical literature on mass incarceration focuses on men, largely because of fewer women and masculinist assumptions of the carceral system. This paper looks specifically at how women's reproduction is experienced and managed by carceral institutions, and how mass incarceration itself is a reproductive technology. Based on ethnographic fieldwork at a women's jail, I explore pregnancy and motherhood behind bars. Certain types of mothering are foreclosed, while an idealized version of maternal identity is simultaneously promoted. For many incarcerated women, jail is the only place where they can experience this form of motherhood, as forces of structural violence outside of jail often limit their ability to parent, such as involvement of child welfare institutions, addiction and homelessness. The myriad ways in which incarcerated women's reproduction is suppressed and enabled is a critical lens through which to understand how institutions and forces of racial oppression reinforce idealized notions of motherhood while making them categorically unattainable.