[Association between vitamin D level and lipid metabolism during second trimester]

Objective: To explore the relationship between the vitamin D levels and lipid metabolism during second trimester. Methods: A total of 1 875 pregnant women who were in the second trimester and had antenatal care in 3 hospitals in Hefei of Anhui province from March 2015 to February 2018 were included. Baseline questionnaire survey was performed, and fasting venous blood samples were collected from the pregnant women to detect serum 25(OH)D, cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C) levels. Cubic non-linear model and linear regression model were used to analyze the linear relationship between vitamin D levels and lipid metabolism indicators in the second trimester. Results: The vitamin D deficiency rate was 75.3% (1 412/1 875) in the pregnant women. The mean levels of lipid metabolism indicators TC, TG, HDL-C and LDL-C were (233.22±38.87), (226.24±83.88), (79.04±12.77), and (109.54±25.95) mg/dl respectively. Multivariate linear regression model results showed, compared with Q5 of the 25(OH)D, the TC and TG levels of Q1-Q4 groups significantly increased, and the LDL-C of Q1 and Q2 groups significantly increased. The highest difference between TC, TG and LDL-C was observed in Q1 group. (TC: β=16.88, 95%CI: 10.50-23.26; TG: β=34.92, 95%CI: 21.32-48.53; LDL-C: β=9.06, 95%CI: 4.77-13.35). No significant differences in HDL-C level among the 5 groups were observed. When stratified with vitamin D deficiency the results showed that, when 25(OH)D was <50 nmol/L, TC, TG and LDL-C levels decreased by 3.53 (95%CI: 1.30-5.75), 7.42 (95%CI: 2.41 to 12.44) and 2.08 mg/dl (95%CI: 0.60-3.57) along with a 10 nmol/L increase of 25(OH)D, the difference was statistically significant, and when 25(OH)D was ≥50 nmol/L, no significant correlation was found between 25(OH)D level and TC, TG and LDL-C levels. No significant relationship between 25(OH)D level and HDL-C level was observed regardless of vitamin D deficiency. Conclusions: There was a nonlinear relationship between vitamin D levels and lipid metabolism indicators in the second trimester. There was a significant negative correlation between 25(OH)D level and lipid metabolism indicators only in the deficiency of vitamin D.