Although Latinas overall have similar or lower rates of preterm birth compared to non-Latina whites, there has been limited understanding about how preterm birth among Latinas might differ based on exposure to societal stressors. Enhanced local immigration enforcement efforts are one such societal stressor that may have negative health impacts for Latinas, as these efforts have been linked to widespread fear of arrest and deportation among Latino communities. Nationally, over half of foreign and U.S.-born Latinos report worrying about deportation for themselves or for family or community members. Our team will evaluate the impact of local immigration enforcement efforts from 2009 to 2015 on differences in preterm birth between Latina and non-Latina white women in California counties. We will use monthly data on arrests and deportations made within each county under the “Secure Communities” program in combination with California birth data and other county-level characteristics.