Serum 25-hydroxycholecalciferol levels in women using oral contraceptives

A study has been made of the serum 25-hydroxycholecalciferol (25-HCC) levels in six groups of women. Significant differences were found between the one pregnant group and the two reference groups as well as between the one pregnant group and two of the three groups using oral contraceptives. No significant differences were found between the reference groups and the ones taking oral contraceptives with oestrogenic concentrations of 0.05 mg or 0.03 mg ethinyl oestradiol for more than one year. It can therefore be concluded that in contrast with most other vitamins, the serum 25-HCC levels are not influenced by the use of oral contraceptives with different oestrogenic concentrations, even over a long period of time.