The deprivations and cruelty of slavery have overshadowed our understanding of the institution's most human dimension: birth. We often don't realize that after the United States stopped importing slaves in 1808, births were more important than ever; slavery and the southern way of life could continue only through babies born in bondage.

In the antebellum South, slaveholders' interest in slave women was matched by physicians struggling to assert their own professional authority over childbirth, and the two began to work together to increase the number of infants born in the slave...