Serum 25-hydroxyvitamin D levels throughout pregnancy: a longitudinal study in healthy and preeclamptic pregnant women.

BACKGROUND

Worldwide there is a high prevalence of 25-hydroxyvitamin D (25OHD) deficiency and has been associated with adverse outcomes during pregnancy.

OBJECTIVE

This is a nested, case-control study in a longitudinal cohort to compare the serum 25OHD levels and other biomarkers throughout pregnancy in a group of 20 preeclamptic women and 61 healthy pregnant women. An additional group of 29 healthy non-pregnant women were also studied during the two phases of the menstrual cycle.

RESULTS

Mean 25OHD levels in non-pregnant women were 31.9 ng/mL and 34.9 ng/mL during follicular and luteal phase, respectively ( < 0.01). Mean serum 25OHD levels in healthy pregnant women were 26.5, 30.1 and 31.9 ng/mL, at first, second and third trimester, respectively ( < 0.001). The first trimester levels of 25OHD were lower than those of healthy non-pregnant women ( < 0.001), showing a significant recovery at third trimester. In the group of healthy pregnant women, the 25OHD levels were 25.7 ng/mL and 27.2 ng/mL at 3 and 6 months postpartum, respectively; both values were lower than those observed in the non-pregnant women ( < 0.001). In preeclamptic women, 25OHD serum levels were similar to those of healthy pregnant women; nevertheless, they remained almost unchanged throughout pregnancy.

CONCLUSION

There were no significant differences between healthy and preeclamptic pregnant women in terms of 25OHD levels throughout the pregnancy. Serum 25OHD levels in non-pregnant women were higher during luteal phase compared with follicular phase. The 25OHD levels of non-pregnant women tended to be higher than those of pregnant women.