Association between the serum vitamin D level and prevalence of obesity/abdominal obesity in women with infertility: a cross-sectional study of the National Health and Nutrition Examination Survey data

Aims To explore the relationship between vitamin D and obesity and abdominal obesity in women with infertility. Material and methods We screened the data from National Health and Nutrition Examination Survey (NHANES) 2013-2016. A total of 201 infertile women between the ages of 20 and 40 years were included in our study. To estimate the independent association of vitamin D with obesity and abdominal obesity, we used weighted multivariate logistic regression models and cubic spline analyses. Results Among infertile women in the NHANES 2013-2016 database, serum vitamin D levels were significantly and negatively associated with body mass index (ss= -0.96, 95% CI: -1.40, -0.51, p < 0.001)and waist circumference (ss= -0.40, 95% CI: -0.59, -0.22, p < 0.001), respectively. After multivariable adjustment, lower vitamin D levels were found to be associated with a higher prevalence of obesity (OR: 8.290, 95% CI: 2.451-28.039, p for trend = 0.001) and abdominal obesity (OR: 4.820, 95%CI: 1.351-17.194, p for trend =0.037). Spline regression showed linearity of the associations between vitamin D and obesity/abdominal obesity (p for nonlinearity > 0.05). Conclusion Our findings suggested that a decreased vitamin D might correspond to a higher prevalence of obesity in infertile women, which reminded us to pay more attention to the supplement of vitamin D in obese infertile women.