† These authors contributed equally.
This study was aimed to investigate the effect of vitamin E (Vit E) supplementation on endometrial thickness and pregnancy outcomes in infertile women. The literature was screened by two researchers and the data was extracted by searching published literature from 1999 to 2020 in the Cochrane library, PubMed, and Embase database. Seven clinical trials were included, with a total of 652 subjects. Here we found the mean endometrium was thicker in Vit E treatment group than that in the control group [SMD = 0.57, 95% CI (0.26, 0.87), P = 0.0002]. Subgroup analysis showed that no significant effect between administration of 400 IU (267 mg) or 100 mg Vit E per day. There was no significant difference between with or without Vit E on ongoing pregnancy rate [OR = 1.08, 95% CI (0.72, 1.62), P = 0.70]. The current evidence demonstrates that Vit E supplementation may increase endometrial thickness in women of reproductive age.