Vitamin D Binding Protein (VDBP) significantly increases during pregnancy. This increase leads to a decrease in the free 25OH Vitamin D concentration, at constant total 25OH Vitamin D levels. Therefore several research groups have studied the importance of free 25OH Vitamin D during pregnancy.

  • JONES K.S. (2016)

Vitamin D expenditure is not altered in pregnancy and lactation despite changes in vitamin D metabolite concentrations.

Scientific Reports 6, Article number: 26795.

  • SCHWARTZ J.B. (2014)

A comparison of direct and calculated free 25(OH) Vitamin D levels in clinical populations.

J.Clin. Endocrinol. Metab., 99(5):1631-7.

  • BIKLE D. (2013)

Variability in free 25(OH) vitamin D levels in clinical populations.

  1. Steroid Biochem. Mol. Biol., S0960-0760.

  • THADHANI R. (2010)

First trimester vitamin D, vitamin D binding protein, and subsequent preeclampsia.

Hypertension, 56(4):758-63.