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 ( < 0.001). The [25(OH) D] level of lower than 30 ng/ml was observed in 43.5% of the control group ( = 27) and 71.4% of the case group ( = 45;  = 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 ( < 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.