Healthy women using hormonal contraception were more likely to have higher levels of total 25-hydroxyvitamin D vs. women not using hormonal contraception, although levels of free 25-(OH)D were similar between the groups, according to findings from a post hoc analysis of a randomized controlled trial.

The use of hormonal contraceptives has been associated with higher levels of vitamin D binding protein and higher concentrations of total 25-(OH)D in most, but not all studies, Stefan Pilz, MD, PhD, of the division of endocrinology and diabetology at the Medical University of Graz, Austria, and colleagues wrote in the study background. However, the association between hormonal contraception use and levels of free 25-(OH)D levels is largely unknown.