Objective To analyze the influencing of vascular endothelial growth factor (VEGF) gene polymorphism on success rate of embryo implantation in patients with thin endometrium.

Methods A total of 100 patients with thin endometrium from the gynecological outpatient and inpatient departments of the hospital from June 2022 to December 2023 were selected as study group, and another 100 healthy adult women from the physical examination department in the same period were selected as control group. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the single nucleotide polymorphism at four different loci of the VEGF gene. Allele-specific PCR (AS-PCR) was used to analyze the distribution of VEGF genotypes and allele frequencies at the corresponding loci in both groups. The study group underwent frozen-thawed embryo transfer (FET), and their pregnancy conditions were confirmed by ultrasound 30 to 35 days later. Based on pregnancy outcomes, the study group was divided into successful pregnancy group and failed pregnancy group, and VEGF gene polymorphism between the two groups was compared. Logistic regression analysis was conducted to investigate the influence of VEGF gene polymorphism on pregnancy outcomes in patients with thin endometrium. Receiver operating characteristic (ROC) curve was plotted to assess the predictive value of VEGF gene polymorphism for pregnancy failure in patients with thin endometrium.

Results Compared with the AA+CA genotype at the -2578C/A locus, patients carrying the CC genotype had increased risk of developing thin endometrium by 1.412 times (95%CI, 1.004 to 1.985), and the allelic mutation C showed increased risk by 1.526 times (95%CI, 1.066 to 2.186). Similarly, compared with the GA+AA genotype at the -1154G/A locus, patients carrying the GG genotype had increased risk of developing thin endometrium by 1.467 times (95%CI, 1.011 to 2.128), and the allelic mutation G showed increased risk by 1.531 times (95%CI, 1.026 to 2.284). There were no significant differences in VEGF gene genotypes and allele distributions at the -460C/T and +936C/T loci between the two groups (P>0.05). Among the 100 patients with thin endometrium in the study group, 40 cases had successful pregnancies after FET. There were significant differences in the distribution of VEGF gene genotypes at the -2578C/A and -1154G/A loci between the successful pregnancy group and the failed pregnancy group (P < 0.05). Logistic regression analysis revealed that carrying the CC genotype at the -2578C/A locus and the GG genotype at the -1154G/A locus were risk factors for pregnancy outcomes in patients with thin endometrium (OR>1, P < 0.05). The ROC curve showed that the area under the curve (AUC) for predicting pregnancy failure in patients with thin endometrium based on VEGF gene polymorphisms at the -2578C/A and -1154G/A loci was 0.801(95%CI, 0.552 to 0.838).

Conclusion Carrying the CC genotype at the -2578C/A locus and the GG genotype at the -1154G/A locus can increase the risk of developing thin endometrium and reduce the success rate of pregnancy in patients with thin endometrium. Moreover, VEGF gene polymorphisms at the -2578C/A and -1154G/A loci can effectively predict the risk of pregnancy failure in patients with thin endometrium.