Objectives: Whether the maternal vitamin D deficiency is associated with preeclampsia is still an argument. We aimed to assess the association between maternal serum 25-hydroxyvitamin D [25(OH)D] concentrations and risk of preeclampsia in a Chinese population and systematically evaluate published evidence on this association.
Methods: We conducted a nested case-control study involving 122 pregnant women with preeclampsia and 488 pregnant women whose blood pressure was within the normal range (as controls). For further meta-analysis, 20 studies and our study were included for the final pooled analysis, involving 39,031 participants and 3305 preeclampsia cases with various ethnicities.
Results: The results showed that 65.6% of women with preeclampsia had serum 25(OH)D concentrations <50.0 nmol L-1 compared with 55.3% of women in controls. The 25(OH)D concentrations were significantly lower in women with preeclampsia than controls [Median (IQR), women with preeclampsia versus controls: 43.3 (35.5, 55.2) versus 47.5 (37.6, 60.4) nmol L-1, p = .014]. For women with 25(OH)D concentrations <50.0 nmol L-1, they had a 65% increase in preeclampsia risk (95% CI = 1.02-2.69), as compared with women with 25(OH)D concentrations from 50.0 to 74.9 nmol L-1. Further, meta-analysis showed that low 25(OH)D concentrations were associated with a significantly increased risk of preeclampsia by 62% (pooled OR = 1.62, 95%CI = 1.36-1.94), and the risk effect of low 25(OH)D concentrations existed in most subgroups.
Conclusions: Low 25(OH)D concentration in pregnancy was significantly associated with preeclampsia risk, and it may serve as biomarkers for the surveillance of high-risk pregnant women.
Keywords: 25(OH)D; meta-analysis; preeclampsia; risk; vitamin D.