Abstract: Received: 19 November 2021 | Accepted: 17 January 2022 DOI: 10.1002/jmv.27606 RESEARCH ARTICLE Oxidative stress status and vitamin D levels of asymptomatic to mild symptomatic COVID‐19 infections during the third trimester of pregnancy: A retrospective study in Metz, France Guillaume Schmitt1,2 | Sary Labdouni2 | Catherine Delamare2 | Jaouad Bouayed1 1 Université de Lorraine, LCOMS /Neurotoxicologie Alimentaire et Bioactivité, Metz, France Rachid Soulimani1 | Abstract It is believed that the subtle equilibrium between tolerance and immunity during the 2 CHR Metz‐Thionvillle Hôpital de Mercy, Ars‐ Laquenexy, France unique biological state of pregnancy, which is characterized by further physiological and hormonal changes, rends pregnant women more vulnerable to coronavirus Correspondence Jaouad Bouayed, Université de Lorraine, LCOMS/Neurotoxicologie Alimentaire et Bioactivité, Metz 57000, France. Email: jaouad.bouayed@univ-lorraine.fr disease 2019 (COVID‐19). In this retrospective study, confirmed COVID‐19‐positive pregnant women (n = 15) during their third trimester, comprising asymptomatic (n = 7) and mild symptomatic (n = 8), and healthy pregnant controls (n = 20), were enrolled between June 1, 2020 and June 1, 2021 from the Hospital CHR Metz‐ Thionville in Metz, France. Vitamin D concentrations, C‐reactive protein (CRP), and oxidative stress markers including superoxide dismutase (SOD), catalase (CAT), reduced (GSH) and oxidized (GSSG) glutathione levels, hydrogen peroxide (H2O2), and the total antioxidant capacity, measured the ferric reducing ability of plasma (FRAP), were evaluated in the serum of patients and controls. Results showed that all pregnant women (patients and controls) enrolled in this study were vitamin D deficient (<20 ng/ml). However, mild COVID‐19 pregnant women were severely vitamin D deficient (<12 ng/ml), which may suggest a link between vitamin D deficiency and the symptomatology of COVID‐19 illness in singleton pregnancy. No differences between the levels of CRP and the majority of the studied oxidative stress markers in COVID‐19‐positive pregnant women (asymptomatic and/or mildly symptomatic patients) versus COVID‐19‐negative pregnant women were found, suggesting the absence or a low magnitude of oxidative stress in pregnant women with COVID‐19. This may also explain the absence of severe courses of COVID‐19 infection. More studies are warranted to investigate the role of vitamin D supplementation and antioxidant‐rich diets in the prevention against severe forms of COVID‐19 in pregnant women. KEYWORDS COVID‐19, C‐reactive protein (CRP), oxidative stress, pregnancy, SARS‐CoV‐2, vitamin D J Med Virol. 2022;1–7. wileyonlinelibrary.com/journal/jmv © 2022 Wiley Periodicals LLC | 1 2 | 1 | INTRODUCTION SCHMITT ET AL. In this retrospective study, healthy control pregnant women and confirmed COVID‐19 patients without comorbidities including mildly The coronavirus disease 2019 (COVID‐19) caused by the severe acute symptomatic and asymptomatic patients were enrolled in their third respiratory syndrome coronavirus 2 (SARS‐CoV‐2), a novel betacor- trimester. We retrospectively evaluated the serum oxidative stress onavirus, has been declared as a global pandemic by the World Health status of pregnant women with and without COVID‐19, their in- Organization (WHO) on March 11, 2020.1 Until today, the ongoing flammatory status, and also their serum vitamin D levels. To the best COVID‐19..