Relationship between vitamin D status in pregnancy and the risk for preeclampsia: A nested case-control study

Vitamin D is thought to be involved in the pathogenesis of preeclampsia. To evaluate the relationship between vitamin D insufficiency in the first trimester of pregnancy and preeclampsia.

Nested case-control study (FEPED study) in type 3 obstetrical units. Pregnant women from 10 to 15 WA. For each patient with preeclampsia, 4 controls were selected from the cohort and matched by parity, skin color, maternal age, season and BMI. The main outcome measure was serum 25(OH)D status in the first trimester.

83 cases of preeclampsia were matched with 319 controls. Mean 25(OH)D levels in the first trimester were 20.1 ± 9.3 ng/mL in cases and 22.3 ± 11.1 ng/mL in controls (p = 0.09). The risk for preeclampsia with 25(OH)D level ≥30 ng/mL in the first trimester was decreased, but did not achieve statistical significance (OR, 0.57; 95% CI, 0.30-1.01; p = 0.09). High 25(OH)D during the 3rd trimester was associated with a significantly decreased risk of preeclampsia (OR, 0.43; 95%CI, 0.23-0.80; p = 0.008). When women with 25(OH)D levels <30 ng/mL both in the first and 3rd trimesters ("low-low") were taken as references, OR for preeclampsia was 0.59 (95% CI, 0.31-1.14; p = 0.12) for "low-high" or "high-low" women and 0.34 (95% CI, 0.13-0.86; p = 0.02) for "high-high" women.

No significant association between preeclampsia and vitamin D insufficiency in the first trimester was evidenced. However, women with vitamin D sufficiency during the 3rd trimester and both in the first and 3rd trimesters had a significantly lower risk of preeclampsia.