Associations of vitamins D3 and K2 supplementation on fetal growth restriction-related skeletal development abnormalities and their potential mechanisms

Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality and is often associated with placental dysfunction and impaired angiogenesis. Although vitamin D3 (VD3) and vitamin K2 (VK2) are involved in vascular regulation, their potential associations with FGR and related molecular mechanisms remain incompletely understood. A retrospective cohort study was conducted involving 200 pregnancies diagnosed with FGR, of whom 98 received adjunct VD3+VK2 supplementation and 102 received standard management alone. Birthweight Z-scores, severe FGR, perinatal outcomes, skeletal development indicators, placental pathology, and maternal metabolic markers were compared. Transcriptomic analysis (GSE24129) was used to identify VD3+VK2-related FGR genes. Differentially expressed genes (DEGs) were intersected with VD3/VK2 predicted targets, followed by protein–protein interaction (PPI) network construction, hub gene analysis, and multi-algorithm machine learning (SVM-RFE, LASSO, random forest). VD3+VK2 supplementation was significantly associated with higher birthweight Z-scores ( β =0.19, P =0.009), a lower risk of severe FGR (adjusted OR=0.57, P =0.041), and reduced composite adverse perinatal outcomes (adjusted OR=0.52, P =0.037). Neonatal skeletal indices, placental weight, and placental pathology scores also improved. Bioinformatics identified 52 VD3+VK2-related FGR genes and 10 hub genes, among which THBS1 emerged as the only consistent key feature across three machine-learning algorithms. In vitro, combined VD3+VK2 treatment was associated with attenuation of H 2 O 2 -induced endothelial injury, reduced THBS1, and partial restoration of cell viability, migration, and tube formation; forced THBS1 overexpression reversed these beneficial effects. Adjunct VD3+VK2 supplementation is associated with improved fetal growth and perinatal outcomes in pregnancies complicated by FGR. The present findings also suggest a potential association between THBS1-related endothelial responses and the observed effects of combined VD3+VK2 treatment. Further prospective and mechanistic studies are warranted to validate these observations and clarify the potential clinical relevance of VD3+VK2 supplementation in FGR management.