LGALS13 encodes galectin-13, also known as placental protein 13 (PP13), a glycan-binding protein with critical roles in placental development and immune regulation during pregnancy 1. The protein is predominantly expressed in syncytiotrophoblast cells and released into maternal circulation as exosomes or microvesicles 2. PP13 binds β-galactosides through its conserved carbohydrate recognition domain and exhibits hemagglutinating activity 2. Functionally, PP13 serves as a potent immunoregulatory molecule that induces apoptosis in activated T cells and diverts immune cells in maternal decidua, thereby protecting pregnancy by conferring maternal-fetal immune tolerance 1. The protein also promotes vasodilation during placentation and vascularization 2. Clinically, LGALS13 variants are associated with pregnancy complications: genetic polymorphisms (rs2233706 and rs2233708) increase risk of infection-associated spontaneous preterm birth 3, while a novel 221delT deletion variant elevates preterm labor risk 4. Decreased placental PP13 expression and low first-trimester maternal serum concentrations are associated with elevated preeclampsia risk, making PP13 a valuable early biomarker for pregnancy complications 12. Additionally, LGALS13 overexpression correlates with better prognosis in ovarian cancer patients 5.