ABSTRACT In response to NOT-OD-20-120, we submit this competitive revision of grant # R01 HD091218 04 (Mechanisms of Zika Virus Maternal-Fetal Transmission) to investigate the impact of COVID-19 and testing for the causative virus, SARS-CoV-2, among pregnant women and their infants. Pregnant women are a vulnerable and high-risk population, as COVID-19 is associated with an increased risk of preterm birth, cesarean section, and maternal intensive care. The objectives of this study are to: (a) evaluate the full impact of SARS-CoV-2 in pregnancy to inform testing strategies, (b) examine the factors that impede testing during pregnancy, and (c) use study data to devise implementation strategies that improve SARS-CoV-2 testing in pregnancy and prenatal care during the pandemic. To do so, we propose to prospectively enroll two cohorts of pregnant women: 1) exposed (SARS-CoV-2 positive), and 2) unexposed (SARS-CoV-2 negative as defined by antibody testing at the beginning of pregnancy, every trimester, and at delivery). Women who initially enroll as unexposed but later test positive for SARS-CoV-2 antibodies will cross over to the exposed cohort. In total, an estimated 179 pregnant women will be followed per cohort. In Aim 1, we will evaluate patients' and providers' perceptions of SARS-CoV-2 testing during pregnancy and the influence of COVID-19 on maternal care- seeking behavior and anxiety via surveys and semi-structured interviews. We hypothesize suboptimal uptake of testing among pregnant women due to the fear of repercussions from a positive test. In Aim 2, we will determine the effect of SARS-CoV-2 infection during pregnancy on the risk of preterm birth and other adverse pregnancy outcomes in symptomatic and asymptomatic disease. We hypothesize that SARS-CoV-2 infection will increase the risk of preterm birth by 12%, regardless of disease severity. In Aim 3, we will estimate the risk of mother-to-fetus SARS-CoV-2 transmission and viral presence in umbilical cord blood, placenta, and amniotic fluid by assaying for viral RNA in the neonate, cord blood, and placenta. We hypothesize that SARS- CoV-2 can be transmitted from mother to fetus. Collectively, Aims 1-3 will be interpreted by investigators, our Scientific Advisory Board (experts in obstetrics, infectious disease, implementation science, disparities) and our Community Advisory Board (an obstetric social worker, pregnant women, and a director of a community obstetrics clinic) who will apply data to devising targeted implementation strategies designed for rapid community dissemination to improve testing and prenatal care. In sum, this study will fill knowledge gaps on the impact of SARS-CoV-2 infection and current utilization of diagnostic testing in pregnancy. Further, it will create implementation strategies to overcome barriers to testing, increase uptake, and promote acceptance and sustainability of testing. Lastly, this study will help determine optimal testing strategies by examining the ...