Is the length of time between endometrial scratching and embryo transfer important for pregnancy success? An observational study

OBJECTIVE: This study sought to evaluate the influence of time (early <90 days and late >90 days) and endometrial injury on pregnancy success. METHODS: This is a retrospective study in which all infertile women who underwent at least one in vitro fertilization cycle at Clinica Gera between 2010 and 2015 were considered for inclusion. We included patients with a normal ovarian reserve and regular menses at intervals of up to 30 days. A total of 315 patient files were reviewed, and the study group was composed of patients who faced fertility issues and had male-caused infertility or idiopathic infertility. Also, women with male or unknown cause of infertility who have performed endometrial biopsy and have undergone embryo transfer up to 180 days after this procedure between 2010 and 2015 were included. The patients were divided into two groups according to the interval between biopsy and embryo transfer: group 1 (early—an interval of <90 days) and group 2 (late—an interval of >90 days and up to 180 days). RESULTS: The results were superior for the group with an interval of less than 90 days relative to the group with an interval of more than 90 days (p<0.04). The pregnancy rates for group 1 and group 2 were 58.5% and 43.4%, respectively. The odds ratio for pregnancy success was 1.63 (95% confidence interval: 1.04 to 2.55). CONCLUSION: The early transfer of embryos (<90 days) may produce better results with a high rate of pregnancy. Further studies are necessary to identify the mechanism involved in this phenomenon.