Cap-Score™ prospectively predicts probability of pregnancy

Mol Reprod Dev. 2018 Aug;85(8-9):654-664. doi: 10.1002/mrd.23057. Epub 2018 Sep 25.


Semen analysis (SA) poorly predicts male fertility, because it does not assess sperm fertilizing ability. The percentage of capacitated sperm determined by GM1 localization ("Cap-Score™"), differs between cohorts of fertile and potentially infertile men, and retrospectively, between men conceiving or failing to conceive by intrauterine insemination (IUI). Here, we prospectively tested whether Cap-Score can predict male fertility with the outcome being clinical pregnancy within ≤3 IUI cycles. Cap-Score and SA were performed (n = 208) with outcomes initially available for 91 men. Men were predicted to have either low (n = 47) or high (n = 44) chance of generating pregnancy using previously-defined Cap-Score reference ranges. Absolute and cumulative pregnancy rates were reduced in men predicted to have low pregnancy rates versus high ([absolute: 10.6% vs. 29.5%; p = 0.04]; [cumulative: 4.3% vs. 18.2%, 9.9% vs. 29.1%, and 14.0% vs. 32.8% for cycles 1-3; n = 91, 64, and 41; p = 0.02]). Only Cap-Score, not male/female age or SA results, differed significantly between outcome groups. Logistic regression evaluated Cap-Score and SA results relative to the probability of generating pregnancy (PGP) for men who were successful in, or completed, three IUI cycles (n = 57). Cap-Score was significantly related to PGP (p = 0.01). The model fit was then tested with 67 additional patients (n = 124; five clinics); the equation changed minimally, but fit improved (p < 0.001; margin of error: 4%). The Akaike Information Criterion found the best model used Cap-Score as the only predictor. These data show that Cap-Score provides a practical, predictive assessment of male fertility, with applications in assisted reproduction and treatment of male infertility.

Keywords: capacitation; human; infertility; male fertility; semen analysis (SA); sperm.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Feasibility Studies
  • Female
  • Fertility
  • Fertilization / physiology
  • Humans
  • Infertility, Male / diagnosis*
  • Kaplan-Meier Estimate
  • Logistic Models
  • Male
  • Pregnancy Outcome
  • Pregnancy Rate
  • Pregnancy*
  • Probability*
  • Prospective Studies
  • Semen Analysis / methods*
  • Sperm Capacitation*
  • Sperm Motility / physiology