Objective: The aim of this study was to assess the diagnostic accuracy of lung ultrasonography (LUS) and a local clinical triage protocol complicated by varied clinical severities of COVID-19, in pregnant patients who had computed tomography (CT) and reverse transcription polymerase chain reaction (RT-PCR) results. Materials and Methods: This retrospective cohort study was conducted in a tertiary maternity unit, during the pandemic, between March 2020 and November 2021. The pregnant patients included in the study were diagnostically categorized as asymptomatic, mild, moderate, severe, and critical, upon hospital admission and their presenting disease severity. All of the patients, as well as those with mild and asymptomatic severity, LUS were evaluated accuracy based on their RT-PCR results. Results: In total, 1531 pregnant patients underwent a primary emergency department clinical evaluation, in the pandemic clinic. The sensitivity, specificity, positive predictive value, and negative predictive values for LUS were 70.5%, 72.45%, 88.1%, and 45.8%, respectively. Conclusion: In this large cohort of patients, LUS was shown to be quick, safe, effective, and reproducible diagnostic tool for the screening of COVID-19 pneumonia, in this obstetric practice. This clinical evidence also provided a new set of triage strategies, during the pandemic, for pregnant patients.