Vitamin D deficiency and its association with fetal growth restriction in pregnant women

Vitamin D deficiency is common among pregnant women and is associated with an increased risk of obstetric complications, particularly fetal growth restriction (FGR). The main pathogenetic mechanism of FGR is impaired transplacental nutrient transport due to vascular dysfunction and decreased expression of vitamin D receptors (VDR). Aim - to determine serum vitamin D levels in pregnant women and evaluate its role in the development of FGR. Materials and methods. A total of 140 pregnant women were examined: 90 with vitamin D deficiency and FGR (main group), and 50 with optimal 25(OH)D levels and a physiological course of pregnancy (control group). Serum levels of 25(OH)D, parathyroid hormone (PTH), calcium, and phosphorus were assessed. VDR expression in the placenta was evaluated by immunohistochemistry. Placental blood flow was assessed using Doppler ultrasonography, and fetal status was evaluated by ultrasound. Statistical analysis was performed using MedStat v.5.2 and EZR v.3.4.1, with a significance level of p<0.05. Results. The mean serum 25(OH)D level in the main group was 15.2±5.1 ng/mL, compared to 30.5±7.4 ng/mL in the control group. Elevated PTH levels (62.3±9.5 pg/mL), decreased calcium and phosphorus concentrations, and reduced placental VDR expression were observed in the main group. These changes were associated with impaired placental blood flow (increased pulsatility and resistance indices in the umbilical artery) and the development of FGR. Conclusions. Vitamin D deficiency contributes to the development of FGR through disruption of calcium-phosphorus metabolism, downregulation of VDR expression, and placental vascular dysfunction. Timely assessment and correction of vitamin D levels in pregnancy are essential for the prevention of adverse perinatal outcomes. The study was conducted in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the local ethics committee of the participating institution. Informed consent was obtained from all participants. The author declares no conflict of interest.