Abstract: Objective To explore the relationship between vitamin D receptor (VDR) gene pol-ymorphisms at Fok I site and the risk of preterm birth for potential intervention of of preterm birth or threatened premature delivery. Methods Fifty-seven women with preterm birth and 84 with full-term birth were included in this analysis. Polymerase chain reaction-restriction frag-ment length polymorphism (PCR-RFLP) was performed to identify VDR gene Fok I geno-types. Results No significant difference was found in age, D-dimer (DDI), fibrinogen (Fg), serum calcium (Ca2 + ), leukocyte count or glycosylated hemoglobin (HbA1c) level between the women in the preterm and full-term birth groups (P>0.05). The two groups differed signifi-cantly in the distribution of VDR gene Fok I site genotypes and allele frequency of F/F (P<0.05).The frequency of FF genotype was significantly higher in the preterm group than in the full-term group. Compared with Ff and ff genotypes, FF genotype was associated with an in-creased risk of preterm delivery (χ2=9.701, P=9.701, OR=3.320, 95% CI [1.560, 7.066]). In the preterm group, the maternal age, DDI, Fg, serum Ca2 + , leukocyte count or HbA1c did not differ significantly between the genotypes (P>0.05). Conclusion VDR gene Fok I site geno-types are related with preterm birth, and the FF genotype may serve as a potential risk factor for preterm birth.