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

PURPOSE: To investigate the association between vitamin D status and the clinical severity of COVID-19 in pregnant women. METHODS: This prospective case–control study included 147 pregnant women with COVID-19 and 300 matched controls. Serum 25-hydroxyvitamin (25(OH)D) concentrations were measured on admission. Patients with mild-to-moderate disease (n = 114, 77.6%) and severe-to-critical disease (n = 33, 22.4%) were classified as symptomatic patients who did not require oxygen support and those who received oxygen support, respectively. SARS-CoV-2 positivity rates, clinical severity of COVID-19, and pulmonary involvement were compared according to vitamin D status. RESULTS: Serum 25(OH)D concentrations were found to be 36.6 ± 26.8 and 31.3 ± 20.7 nmol/L in pregnant women infected with SARS-CoV-2 and healthy controls, respectively (p = 0.001). The clinical severity of pregnant women with COVID-19 did not differ concerning vitamin D deficiency (RR = 0.568, 95% CI [0.311–1.036]; p = 0.065), even after excluding patients on vitamin supplementation (RR = 0.625, 95% CI [0.275–1.419]; p = 0.261). Testing positive for SARS-CoV-2 was not related to vitamin D status in the overall cohort of pregnant women (RR = 0.767, 95% CI [0.570–1.030]; p = 0.078). Pulmonary involvement of COVID-19 was found to be similar between patients with vitamin D deficiency and adequate vitamin D levels (RR = 0.954; 95% CI [0.863–1.055]; p = 0.357). CONCLUSION: The clinical severity and pulmonary involvement of COVID-19 may not be associated with vitamin D status in pregnant women. Vitamin D deficiency/adequacy rates were comparable in pregnant women infected with SARS-CoV-2 and healthy pregnant women.