Evaluation of Vitamin D Serum Levels in Pregnant Women with COVID-19 Compared with the Control Group in Pregnant Women: A Case–Control Study

The findings of studies on serum 25-hydroxy-vitamin D [25(OH) D] levels in pregnant women with or without coronavirus disease 2019 (COVID-19) were found to be controversial and inadequate. The present study was thus carried out at to fill the gap felt in this regard. In this case–control study, 63 pregnant women with singleton pregnancy who were infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and 62 pregnant women who were matched for gestational age and not infected by COVID-19 were examined. Based on clinical symptoms, the patients with COVID-19 were divided into three groups: mild, moderate, and severe. ELISA method was adopted to measure [25(OH) D] level. The [25(OH) D] means of 23.4 ± 9.2 ng/ml and 31.2 ± 0.15 ng/ml were noted in the case and control groups, respectively (p < 0.001). The [25(OH) D] level of lower than 30 ng/ml was observed in 43.5% of the control group (n = 27) and 71.4% of the case group (n = 45; p = 0.002). Multivariate linear regression analysis to match age, gestational age, [25(OH) D] supplement use, and number of pregnancies showed that [25(OH) D] mean in the case group is 8.2 units lower, compared to the control group (p < 0.001). The [25(OH) D] level in pregnant women with COVID-19 is lower, compared to non-infected pregnant women. However, there is no significant relationship between [25(OH) D] level and disease severity. A sufficient level of [25(OH) D] may protect pregnant women against COVID-19.