[Impact of sperm morphology on pregnancy rates after intrauterine insemination]

Sperm morphology has been used as a prognostic factor in in vitro fertilization, however, in intrauterine insemination (IUI) its predictive role is controversial. The aim of this study was to determine the impact of sperm morphology as isolated parameter of the spermiogram has on the probability of pregnancy in couples that are treated with IUI.

Retrospective study of IUI cycles performed in the Reproductive Medicine Unit of Clínica Las Condes between January 2016 and December 2018. Logistic regression of the following variables: sperm morphology grouped in 0-1%, 2-3% and≥4%, total progressively motile sperm count inseminated, age of the woman and the man.

A total of 385 cases were included and clinical pregnancy was diagnosed in 85 of them. When separating into groups of sperm morphology<4% and≥4%, the pregnancy rate was 22% in both groups. The age of the woman was the only statistically significant factor in the logistic regression. The area under the ROC curve of sperm morphology as a predictor of pregnancy was 0.53.

Our study concludes that sperm morphology should not be considered as a single parameter when deciding whether or not a couple can be treated with IUI, eliminating isolated teratozoospermia as a direct indication for in vitro fertilization. It was not possible to determine a cut-off point for sperm morphology that serves as a predictor of pregnancy.