Objective: Little is known about the demographic and clinical factors associated with SARS-CoV-2 infection in pregnant women in the United States. The objective of this study was to evaluate the factors associated with SARS-CoV-2 infection in women admitted for labor and delivery, in the context of universal screening. Design: Prospective cohort study. Setting: Four Boston-area hospitals. Population: Convenience sample of all women admitted for delivery (n= 1,153). Methods: We reviewed the health records of all women admitted for delivery at the largest health system in Massachusetts between April 19-May 16, 2020. Factors evaluated for potential association with SARS-CoV-2 infection included age, BMI, race, co-morbidities, zip code, infection in a household member, number of children in the household, occupation, and insurance type. Main Outcome Measures: Risk of SARS-CoV-2 infection and associations between SARS-CoV-2 infection and clinical characteristics. Results: A total of 32 patients (2.8%, 95% confidence interval 1.9-3.9) tested positive for SARS-CoV-2 infection on admission for delivery; 24 (75.0%) of the patients who tested positive were asymptomatic. Factors associated with SARS-CoV-2 infection included: younger age, obesity, African-American or Hispanic race/ethnicity, residence in heavily affected communities, household member with known infection, essential worker occupation, and Medicaid insurance. 93.5% of patients testing positive for SARS-CoV-2 had one or more factors associated with disease acquisition. Conclusions: In this large sample of deliveries, SARS-CoV-2 infection was largely concentrated in patients with distinct demographic characteristics. Understanding factors associated with infection may inform public health efforts directed towards at risk populations and serve in counseling pregnant women.