High cumulative E(2) exposure during the follicular phase of IVF cycles has detrimental effects on implantation.

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Purpose Vitamin D deficiency has emerged as another potential risk factor for coronavirus disease (COVID‐19) due to the immunomodulatory effects of 25 hydroxyvitamin D [25 (OH)D]. Vitamin D receptor (VDR) gene polymorphisms such as Fok I, Bsm I, Apa I, and Taq I are also associated with different courses of viral infections. This study aimed to evaluate the association between the VDR gene polymorphism at Fok I, Taq I, Bsm I, and Apa I genotypes and the prognosis of COVID‐19 in respect to vitamin D deficiency. Methods Two‐hundred ninety‐seven patients with COVID‐19 were enrolled. Serum 25 (OH)D levels were measured. Four variant regions of the VDR gene, FokI, BsmI, ApaI, and TaqI were determined. Results Eighty‐three percent of subjects had vitamin D deficiency, and 40.7% of the whole group had severe deficiency. Median 25 (OH)D level was 11.97 ng/ml. Vitamin D levels were not related to inflammatory markers, disease severity, admission to intensive care unit (ICU), and mortality. While disease severity was related to Fok I Ff genotype, it was Taq TT genotype for ICU admission. Moreover, the ApaI aa genotype was common among the patients who were died. None of the deceased subjects had the Fok I FF genotype. Conclusion 25 (OH)D levels were not related to the severity and mortality of COVID‐19. VDR gene polymorphisms are independently associated with the severity of COVID‐19 and the survival of patients.