key: cord-1014484-9ubb8vot
authors: Schmitt, Guillaume; Labdouni, Sary; Soulimani, Rachid; Delamare, Catherine; Bouayed, Jaouad
title: 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
date: 2022-01-27
journal: J Med Virol
DOI: 10.1002/jmv.27606
sha: b7d7699edc41e14ad1f42b523f2ac5fa678706a3
doc_id: 1014484
cord_uid: 9ubb8vot

It is believed that the subtle equilibrium between tolerance and immunity during the unique biological state of pregnancy, which is characterized by further physiological and hormonal changes, rends pregnant women more vulnerable to coronavirus 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 (H(2)O(2)), 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.

The coronavirus disease 2019 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel betacoronavirus, has been declared as a global pandemic by the World Health Organization (WHO) on March 11, 2020. 1 Until today, the ongoing COVID-19 pandemic has affected >346 million people and killed >5.5 million people worldwide. It is thought that pregnant women constitute a vulnerable population to COVID-19 infection, owing to a myriad of adaptive physiological modifications accompanying pregnancy, including a relative immune suppression, edema of respiratory tract mucosa, diaphragm elevation, and increased oxygen consumption. [2] [3] [4] Even if it is believed that immunosuppression is fundamental to a successful pregnancy (e.g., to render the mother immunologically tolerant to the fetus), evidence has shown that maternal immune response is rather highly dynamic, as the immunological stages change following the trimesters, for example, switching from an anti-inflammatory status, a landmark of the second trimester, to a proinflammatory status during the third trimester that is necessary for labor and delivery (reviewed in Reference [5] ). Compared with nonpregnant women of reproductive age, a systematic review has shown that pregnant women present a significantly higher susceptibility to develop severe COVID-19. 6 Other factors were also considered as playing a significant role in the severity of COVID-19. This included higher BMI, increased maternal age, less access to health care, comorbidities such as preexisting diabetes and chronic hypertension, vitamin D and nutritional deficiencies, oxidative stress, hyperactive microglia, human genetic variation such as certain mutations in TYK2 and the genomic segment on chromosome 3 that has been inherited from Neanderthals. [6] [7] [8] [9] [10] For instance, in a large cohort retrospective study, it has been suggested that pregnant women with clinical comorbidities were more susceptible to COVID-19 infection. 11 It has been further suggested that fetal sex influences maternal immune responses (e.g., maternal titers of IgG antibodies) to SARS-CoV-2 during pregnancy. 12 Recently, the capacity of SARS-CoV-2 to infect and propagate in the placenta, a fetal-derived tissue, 12 has been demonstrated. 13 However, no association was found between COVID-19 and miscarriage, spontaneous preterm delivery, intrauterine fetal SARS-CoV-2 infection, and the birth weight of newborns. 3,14-16 Nevertheless, in a prospective cohort study, although no SARS-CoV-2 vertical transmission to newborns occurred, authors have rather found a high association between COVID-19 and preeclampsia, preterm delivery, and cesarean section compared with non-COVID-19 pregnant women. 4 Such adverse COVID-19 outcomes including stillbirth were also highlighted in a large cohort study, 17 and it is thought that up to 40% of women with COVID-19 are concerned by the above-listed pregnancy complications. 13 Divergences in results between researchers on COVID-19 outcomes in pregnant women could be explained by several factors.

This included the trimester of pregnancy when infection occurred, the numerous forms of COVID-19, including asymptomatic and mildly to critical illness, the presence of comorbidities such as obesity and diabetes, women's age, SARS-CoV-2 viral load, the differences in the control group used in the studies (e.g., non-COVID-19 pregnant women or non-pregnant women), among others.

In this retrospective study, healthy control pregnant women and confirmed COVID-19 patients without comorbidities including mildly symptomatic and asymptomatic patients were enrolled in their third trimester. We retrospectively evaluated the serum oxidative stress status of pregnant women with and without COVID-19, their inflammatory status, and also their serum vitamin D levels. To the best of our knowledge, this is the first study that aimed to examine whether oxidative stress disturbances and vitamin D deficiency were associated with confirmed mild COVID-19 and asymptomatic forms during the third trimester of singleton pregnancy. (Table 1) .

As for controls used in this study, 20 COVID-19-negative pregnant women were selected from the above cohort, with the following inclusion criteria: singleton pregnancy in the third trimester with a serum sample (~1 ml) collected within 15 days after the RT-PCR negativity.

The average age of the controls was 31 years (range: 20−35), with a median gestational age of 37.5 WA.

Except for one patient with allergies, all pregnant women controls as well as patients were without any comorbidity.

In this retrospective study, analyzed serum samples were leftovers in CHR Metz-Thionville hospital laboratories. They were processed in accordance with existing regulations and guidelines of the French Commission for Data Protection (Commission Nationale de l'Informatique et des Libertés). They were completely anonymous, and it was not possible to return to individual patient files. According to the French law, no informed consent is required for processing leftover samples. 

C-reactive protein (CRP) was used as a marker of inflammation. CRP concentrations (mg/L) were evaluated in serums by immunoturbidimetry using an Automate AU (Beckman Coulter A98856).

In this study, all oxidative stress markers were assessed in the serum of pregnant women (controls and patients) by colorimetric assays, 

All data were analyzed based on non-parametric statistical tests. The

Kruskal-Wallis test was used to compare between-group variables, followed by the Wilcoxon−Mann−Whitney test that was used to compare patients (asymptomatics and/or symptomatics) to the controls. The data were reported as the median (interquartile range [IQR] ). Significance was set at p ≤ 0.05. All of the statistical analyses were performed using R statistical software. 

Pregnancy is regarded as a unique biological or immunological state that favors increased vulnerability to infections, including more severe COVID-19. 12,18 Vitamin D plays an important role in the immune system and many physiological functions, acting as an antiinflammatory, antiviral, and antioxidant agent, among others. 10, 18 Vitamin D deficiency constitutes a widespread health issue among pregnant women that may aggravate pregnancy outcomes, for example, by increasing the risk of gestational diabetes, pre-eclampsia, and preterm birth. [19] [20] [21] Interestingly, a strong relationship was observed between vitamin D deficiency and both COVID-19 positivity and COVID-19 severity. 10, 22 For example, in a retrospective cohort study enrolling 227 COVID-19 patients, it was found that 94% had vitamin D deficiency, and it was estimated that severe vitamin D deficiency was 30% higher in COVID-19 patients than in the general population. 10 In the present study, we have found a significantly 18.76 ng/ml, respectively). 19 Additionally, pregnant women with moderate/severe COVID-19 presented severe vitamin D deficiency induce the other one, leading to a negative vicious circle. [35] [36] [37] To the best of our knowledge, our work constitutes the first study evaluating serum oxidative status of pregnant women with COVID-19 infection versus healthy control pregnant women during the third trimester of pregnancy. Previously, placental oxidative stress in mothers with COVID-19 illness has been found. 35 In the present study, we have evaluated oxidative stress markers including 

The main strengths of the present study were its novelty, its focus on the third trimester of singleton pregnancy, and its design enrolling COVID-19 patients without comorbidities and controls constituted by healthy pregnant women. However, the main limitation of this retrospective study is the small sample size. In addition, this study did not follow the course of COVID-19 infection in pregnant patients.

This study highlighted vitamin D deficiency during the third trimester of pregnancy in both COVID-19-negative and COVID-19-positive pregnant women. It is important to note that Metz is a city located in the north-east of France, and it is a less sunny region, which may explain, at least partially, vitamin D deficiency in pregnant women enrolled in this study. However, the deficiency was more severe in mild COVID-19, which suggests, at least to some extent, a link be- 

The authors declare that there are no conflict of interests.

In this retrospective study, analyzed serum samples were leftovers in 

The supporting data are available within the article.

http://orcid.org/0000-0002-8410-2105

World Health Organization. WHO timeline-COVID-19

Clinical analysis of ten pregnant women with COVID-19 in Wuhan, China: a retrospective study

Clinical characteristics and intrauterine vertical transmission potential of COVID-19 infection in nine pregnant women: a retrospective review of medical records

Maternal COVID-19 infection, clinical characteristics, pregnancy, and neonatal outcome: a prospective cohort study

The unique immunological and microbial aspects of pregnancy

Effect of coronavirus disease 2019 (COVID-19) on maternal, perinatal and neonatal outcome: systematic review

The link between microglia and the severity of COVID-19: the 'two-hit' hypothesis

The major genetic risk factor for severe COVID-19 is inherited from Neanderthals

Human genetic variants identified that affect COVID susceptibility and severity

Vitamin D deficiency is associated with COVID-19 positivity and severity of the disease

SARS-CoV-2 prevalence and maternal-perinatal outcomes among pregnant women admitted for delivery: experience from COVID-19-dedicated maternity hospital in Jammu, Jammu and Kashmir (India)

Pregnancy influences immune responses to SARS-CoV-2

SARS-CoV-2 can infect and propagate in human placenta explants

Coronavirus disease 2019 in pregnant women: a report based on 116 cases

COVID-19 infection in pregnant women, preterm delivery, birth weight, and vertical transmission: a systematic review and meta-analysis

Clinical characteristics and risk assessment of newborns born to mothers with COVID-19

Clinical characteristics and outcomes of hospitalized women giving birth with and without COVID-19

Vitamin D and COVID-19: role of ACE2, age, gender, and ethnicity

Impact of vitamin D on the course of COVID-19 during pregnancy: a case control study

Vitamin D and pregnancy outcomes

Vitamin D deficiency in mothers, neonates and children

Therapeutic and prognostic role of vitamin D for COVID-19 infection: a systematic review and meta-analysis of 43 observational studies

Current vitamin D status in European and Middle East countries and strategies to prevent vitamin D defciency: a position statement of the European Calcifed Tissue Society

Vitamin D status is not associated with clinical severity of COVID-19 in pregnant women

C-reactive protein (CRP) and its association with periodontal disease: a brief review

Strengthening the immune system and reducing inflammation and oxidative stress through diet and nutrition: considerations during the COVID-19 crisis

Mild or moderate Covid-19

Adapted sickness behavior-why it is not enough to limit the COVID-19 spread?

Dietary derived antioxidants: implications on health

Oxidative stress associated with SARS-Cov-2 (COVID-19) increases the severity of the lung disease-a systematic review

Oxidative stress and inflammation in COVID-19-associated sepsis: the potential role of anti-oxidant therapy in avoiding disease progression

SARS-CoV-2 infection pathogenesis is related to oxidative stress as a response to aggression

Evaluation of oxidative stress level: total antioxidant capacity, total oxidant status and glutathione activity in patients with COVID-19

Common and novel markers for measuring inflammation and oxidative stress ex vivo in research and clinical practice-which to use regarding disease outcomes?

Mitochondrial and oxidative unbalance in placentas from mothers with SARS-CoV-2 infection

Reduction of paw edema and liver oxidative stress in carrageenan-induced acute inflammation by Lobaria pulmonaria and Parmelia caperata, lichen species, in mice

A causal link between oxidative stress and inflammation in cardiovascular and renal complications of diabetes

Reversal of oxidative stress-induced anxiety by inhibition of phosphodiesterase-2 in mice

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