How low is too low? Postwash total motile sperm count effect on pregnancy outcomes in intrauterine insemination.

Intrauterine insemination (IUI) is a frequently used method to treat couples with infertility. There is evidence of decreased pregnancy rates with a total motile sperm count (TMSC) of less than 10 million, yet there remains to be a consensus on semen parameters for which to recommend IUI in the infertile population. The aim of this study was to determine a minimum threshold of TMSC on semen analysis to offer IUI cycles. This is a retrospective cohort study of all IUI cycles at a private practice infertility centre over four years. Our primary outcome of interest was the presence of clinical pregnancy after each cycle. A total of 999 women underwent 2,169 IUI cycles. The overall clinical pregnancy rate was 19.8% per cycle. During the first IUI each woman underwent, there was an increase in clinical pregnancy with increasing TMSC (OR 0.44) for TMSC ≤1 M to (OR 0.99) for TMSC 6-10 M, compared to TMSC >10 M. Among all IUI with a TMSC between 6 and 10 M, pregnancy outcomes improved with morphology >4% (OR 0.84), compared to morphology <4% (OR 0.25), relative to TMSC >10 M. Using receiver operating characteristic curves, we did not identify a TMSC threshold to offer IUI, although there was a positive correlation between TMSC and IUI success.