Maternal vitamin D, oxidative stress, and pre-eclampsia.

Objective To examine the associations between risk of pre-eclampsia and pregnancy levels of maternal 25-hydroxyvitamin D (25[OH]D) and oxidative stress biomarkers. Methods A nested case-control study (n=99; 34 cases; 65 controls) within a prospective pregnancy cohort. Maternal 25(OH)D and oxidative stress markers (six isomers of F2 -isoprostanes; F2 -isoPs) were measured in plasma at 12-18 and 24-26 gestational weeks. Vitamin D deficiency was defined as 25[OH]D less than 50 nmol/L. Results Maternal vitamin D deficiency was associated with increased 8-iso-PGF2α (P = 0.037), 15(R)-PGF2α (P = 0.004), (±)5-iPF2α -VI (P = 0.026) at 12-18 weeks. Vitamin D deficiency was inversely associated with 8-iso-PGF2α (P = 0.019) and (±)5-iPF2α -VI isomer (P = 0.010) at 24-26 weeks. Both maternal vitamin D deficiency (adjusted odds ratio [aOR], 4.79; 95% confidence interval [CI], 1.67-13.75) and increased (±)5-iPF2α -VI (aOR, 2.46; 95% CI, 1.16-5.22) at 24-26 weeks were associated with risk of pre-eclampsia. However, the interaction test between 25(OH)D and (±)5-iPF2α -VI was not significant (P = 0.143). Conclusion Plasma 25(OH)D below 50 nmol/L was associated with increased oxidative stress levels during pregnancy as measured by two F2 -isoP isomers, including the well-studied marker 8-iso-PGF2α . Whether vitamin D-induced oxidative stress mediates the risk of pre-eclampsia warrants future study.