| Summary: | Obesity is associated with lower concentrations of vitamin D [25(OH)D3] in children, adolescents and adults, but it remains unclear whether maternal adiposity influences maternal and foetal concentrations of this vitamin. The objective of this cross-sectional study was to assess the relationship between maternal adiposity and maternal and cord blood concentrations of vitamin D. It involved 101 mother–newborn pairs from a public maternity in Sao Paulo city, Brazil. Demographic, socioeconomic and obstetric data, as well as anthropometry, physical activity and vitamin D supplementation during pregnancy, were investigated. Maternal adiposity was assessed by bioelectrical impedance. Maternal and cord blood concentrations of vitamin D were measured by high-performance liquid chromatography. Two multiple linear regression models that included maternal and cord blood vitamin D concentrations as outcomes and maternal adiposity as independent variable were used. No association was observed between maternal adiposity and maternal or cord blood concentrations of vitamin D. Maternal vitamin D concentration was associated with race, physical activity and vitamin D supplementation (adj. R2 = 0.74). Cord blood vitamin D concentration was associated with maternal vitamin D concentration (adj. R2 = 0.24). Although fat mass quantification is important to understand vitamin D status during all stages of life, this may not be true in pregnancy as race, vitamin D supplementation and physical activity appeared to be more relevant to vitamin D status. Understanding vitamin D metabolism in pregnancy may elucidate how or if adiposity influences maternal vitamin D status and how it impacts vitamin D transport to the foetus.
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