Recent national and state legislation has called attention to stark racial/ethnic disparities in maternal mortality and severe maternal morbidity (SMM), the latter of which is defined as having a life-threatening condition or life-saving procedure during childbirth. Using linked New York City birth and hospitalization data for 2012-14, we examined whether racial and economic spatial polarization is associated with SMM rates, and whether the delivery hospital partially explains the association. Women in ZIP codes with the highest concentration of poor blacks relative to wealthy whites experienced 4.0 cases of SMM per 100 deliveries, compared with 1.7 cases per 100 deliveries among women in the neighborhoods with the lowest concentration (risk difference = 2.4 cases per 100). Thirty-five percent of this difference was attributable to the delivery hospital. Women in highly polarized neighborhoods were most likely to deliver in hospitals located in similarly polarized neighborhoods. Housing policy that targets racial and economic spatial polarization may address a root cause of SMM, while hospital quality improvement may mitigate the impact of such polarization.