This commentary explores four features of the cultural construction of pregnancy and childbirth in the United States: risk categorization as an aspect of reproductive governance, medicalization, intensive mothering with its implications for gender stratification, and the definition of personhood as beginning at conception. The cultural construction of preterm births (those that end before gestation is complete at about 37 weeks) is interwoven with beliefs about risk in pregnancy. Health risk categories overlap with socially stigmatized characteristics and behaviors, opening sub-groups of women up to intensive surveillance and control. The belief that preterm births are preventable and treatable reinforces medical authority and rationalizes the large allocation of resources to specialty (as opposed to primary) maternal and infant care. Expectations for maternal behavior when preterm birth is threatened and when it occurs reinforce norms of intensive mothering, while the ability to keep preterm infants alive reinforces beliefs about fetal personhood. In these ways, the cultural construction of preterm birth in the U.S. holds the broader construction of pregnancy and childbirth in place by raising the stakes of deviation from norms of reproduction to matters of criminality, death, or serious disability.