RARA and vitamin A deficiency: Vitamin A deficiency (< 0.65 μmol/L) disrupts retinoic acid receptor α (RARα)‐mediated gene transcription8, suppresses placental vascular endothelial growth factor (VEGF) expression (Doldo et al. 2015), and reduces maternal‐fetal nutrient transport efficiency (e.g., 30% downregulation of amino acid transporter SNAT216) (Andrès et al. 2024).