Which factors influence the success rate of egg donation programmes with imported vitrified oocytes?

Which factors influence the success rate of egg donation programmes with imported vitrified oocytes?Observational longitudinal cohort study of 431 oocyte donation cycles conducted between January 2015 and February 2019. A total of 398 couples underwent an IVF cycle with imported donated vitrified eggs. All consecutive oocyte donation cycles conducted at the Centre for Reproductive Medicine of the European Hospital in Rome, Italy, were included.A univariable analysis was conducted. Among the demographic characteristics studied, body mass index (BMI) was significantly able to influence outcome. In 49% of unsuccessful cycles, men were overweight, compared with 39.4% in cycles with a positive beta-HCG test (P = 0.03). The relationship between female or donor BMI and treatment outcome, however, was not statistically significant. The day on which the embryo is transferred affects the outcome of the cycle: transferring on day 2 versus day 5 reduces the probability of clinical pregnancy. The relationship between male BMI classes and semen parameters was studied: obese men have a significantly lower sperm concentration than normal-weight men (P = 0.006 after Bonferroni correction). No statistically significant differences were found in semen volume (P = 0.722), sperm morphology (P = 0.100) and motility (P = 0.179) in obese men compared with normal weight men.In addition to the number of oocytes available after warming, male BMI, semen characteristics and blastocyst transfer are critical parameters able to influence the reproductive outcomes of egg donation programmes with imported vitrified oocytes.