Sperm Morphology: History, Challenges, and Impact on Natural and Assisted Fertility
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Purpose of Review
The classification of morphologically normal sperm has been progressively redefined. Concurrently, our understanding of the significance of sperm morphology in relation to male factor infertility has evolved. In this review, we will discuss the evolution of sperm morphology assessment and factors that contribute to its measurement variability. We will examine the impact of sperm morphology on natural pregnancy, IUI, IVF, and ICSI outcomes.
There is a lack of consensus on sperm morphology classification, technique, and inter-observer grading variability. Current evidence suggests sperm morphology has low predictive value for pregnancy success, for both natural and assisted reproduction. Additionally, the threshold for what is considered an adequate percentage of morphologically normal sperm has changed over time. These variables have called into question the relevance of this variable in predicting fertility outcomes.
Our understanding of the impact of sperm morphology on reproductive outcomes continues to evolve and seems to play less of a role than initially thought.
KeywordsSperm morphology Semen analysis Teratozoospermia Infertility Assisted reproductive technology Male factor
Compliance with Ethical Standards
Conflict of Interest
Rachel B. Danis and Mary K. Samplaski each declare no potential conflicts of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
- 5.Organization WH. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. 1st ed. Singapore; 1980.Google Scholar
- 6.Organization WH. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. 2nd ed. Cambridge; 1987.Google Scholar
- 7.Organization WH. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 3rd ed. Cambridge: Cambridge University Press; 1992.Google Scholar
- 8.Organization WH. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 4th ed. Cambridge: Cambridge University Press; 1999.Google Scholar
- 10.Organization WH. WHO laboratory manual for the examination and processing of human semen. 5th ed. Geneva; 2010.Google Scholar
- 20.•• Kovac JR, Smith RP, Cajipe M, Lamb DJ, Lipshultz LI. Men with a complete absence of normal sperm morphology exhibit high rates of success without assisted reproduction. Asian J Androl. 2017;19:39–42. https://doi.org/10.4103/1008-682X.189211. This is an important reference because investigators focused on a subgroup of men with 0% morphologically normal sperm in the setting of a normal hormonal profile, which is an unusual subgroup of men. Taken further, investigators demonstrated that these men could still conceive naturally, without means of ART.
- 21.•• Kohn TP, Kohn JR, Ramasamy R. Effect of sperm morphology on pregnancy success via intrauterine insemination: a systematic review and meta-analysis. J Urol. 2018;199:812–22. https://doi.org/10.1016/j.juro.2017.11.045. This reference is of importance as it is a relatively recent publication, where investigators conducted a large meta-analysis involving 20 observation studies. Investigators excluded total motile count less than 10 million and also restricted studies to include female partner age 25 to 40years. Total motile count and female age could confound fertilization and clinical pregnancy results, so findings in this meta-analysis are less biased given these inclusion and exclusion criteria.
- 22.Monraisin O, Chansel-Debordeaux L, Chiron A, Floret S, Cens S, Bourrinet S, et al. Evaluation of intrauterine insemination practices: a 1-year prospective study in seven French assisted reproduction technology centers. Fertil Steril. 2016;105:1589–93. https://doi.org/10.1016/j.fertnstert.2016.01.039.CrossRefPubMedGoogle Scholar
- 31.•• Erdem M, Erdem A, Mutlu MF, Ozisik S, Yildiz S, Guler I, et al. The impact of sperm morphology on the outcome of intrauterine insemination cycles with gonadotropins in unexplained and male subfertility. Eur J Obstet Gynecol Reprod Biol. 2016;197:120–4. https://doi.org/10.1016/j.ejogrb.2015.12.014. This reference is important as it includes a large sample size, 412 couples with 530 IUI cycles, uses live birth as a primary objective (versus fertilization rate and/or clinical pregnancy rate), and uses couples with unexplained infertility as the control group, which minimizes the contribution of female factors as reasons for infertility.
- 32.Lemmens L, Kos S, Beijer C, Brinkman JW, van der Horst FAL, van den Hoven L, et al. Predictive value of sperm morphology and progressively motile sperm count for pregnancy outcomes in intrauterine insemination. Fertil Steril. 2016;105:1462–8. https://doi.org/10.1016/j.fertnstert.2016.02.012.CrossRefPubMedGoogle Scholar
- 33.Nandi A, Bhide P, Hooper R, Gudi A, Shah A, Khan K, et al. Intrauterine insemination with gonadotropin stimulation or in vitro fertilization for the treatment of unexplained subfertility: a randomized controlled trial. Fertil Steril. 2017;107:1329–1335 e1322. https://doi.org/10.1016/j.fertnstert.2017.03.028.CrossRefPubMedGoogle Scholar
- 35.Hotaling JM, Smith JF, Rosen M, Muller CH, Walsh TJ. The relationship between isolated teratozoospermia and clinical pregnancy after in vitro fertilization with or without intracytoplasmic sperm injection: a systematic review and meta-analysis. Fertil Steril. 2011;95:1141–5. https://doi.org/10.1016/j.fertnstert.2010.09.029.CrossRefPubMedGoogle Scholar
- 41.Keegan BR, Barton S, Sanchez X, Berkeley AS, Krey LC, Grifo J. Isolated teratozoospermia does not affect in vitro fertilization outcome and is not an indication for intracytoplasmic sperm injection. Fertil Steril. 2007;88:1583–8. https://doi.org/10.1016/j.fertnstert.2007.01.057.CrossRefPubMedGoogle Scholar
- 42.Lundin K. The impact of sperm morphology analysis on IVF results. Journal de Gynecologie, Obstetrique et Biologie de la Reproduction. 2007;36 Suppl 3:S69–73. https://doi.org/10.1016/S0368-2315(07)78733-1.
- 44.Grow DR, Oehninger S, Seltman HJ, Toner JP, Swanson RJ, Kruger TF, et al. Sperm morphology as diagnosed by strict criteria: probing the impact of teratozoospermia on fertilization rate and pregnancy outcome in a large in vitro fertilization population. Fertil Steril. 1994;62:559–67.CrossRefGoogle Scholar
- 53.Demko ZP, Simon AL, McCoy RC, Petrov DA, Rabinowitz M. Effects of maternal age on euploidy rates in a large cohort of embryos analyzed with 24-chromosome single-nucleotide polymorphism-based preimplantation genetic screening. Fertil Steril. 2016;105:1307–13. https://doi.org/10.1016/j.fertnstert.2016.01.025.CrossRefPubMedGoogle Scholar
- 63.Wang Y, Yang J, Jia Y, Xiong C, Meng T, Guan H, et al. Variability in the morphologic assessment of human sperm: use of the strict criteria recommended by the World Health Organization in 2010. Fertil Steril. 2014;101:945–9. https://doi.org/10.1016/j.fertnstert.2013.12.047.CrossRefPubMedGoogle Scholar