question: Purpose: To explore the impact of the COVID-19 pandemic on pregnant women’s anxiety and identify factors most strongly associated with greater changes in anxiety. Methods: : An anonymous, online, survey of pregnant women (distributed April 3 - 24, 2020) included a modified Pregnancy-Related Anxiety Scale (PRAS) reflecting respondents’ perception of pregnancy anxiety before COVID-19 and a current assessment of pregnancy-related anxiety. The difference between these scores was used as the outcome variable. Data were analysed using bivariate and multivariate linear regression analyses. Results: : 2,740 pregnant women from 47 states completed the survey. 25.8% (N=706) stopped in-person visits, 15.2% used video visits (N=415), and 31.8% (N=817) used phone visits for prenatal care as a result of COVID-19. Those planning a hospital birth dropped from 2641 (96.4%) to 2400 (87.7%) following COVID-19. More than half of women reported increased stress about food running out (59.2%, N=1622), losing a job or household income (63.7%, N=1745), or loss of childcare (56.3%, N=1543). More than a third reported increasing stress about conflict between household members (37.5%, N=1028), and 93% (N=2556) reported increased stress about getting infected with COVID-19. Slightly less than half of respondents (either selves or family members) were healthcare workers (41.4%, N=1133) or worked in essential services (45.5%, N=1246). In multivariate analysis, those reporting higher agreement with COVID-19-related stressors had greater changes in pre- to post-COVID-19 pregnancy-related anxiety. Conclusions: The COVID-19 pandemic is profoundly affecting pregnant women’s mental health, and factors independent of pregnancy appear to be driving changes in pregnancy-specific anxiety.