Looks May Not Be Everything, but for Sperm They Do Matter
Nov. 7, 2001 -- When it comes to human coupling, good looks rule. All else being equal, attractive people often have a big advantage in finding mates. Now it seems that for men, appearance may be critical at a cellular level as well. New research suggests that having good-looking sperm is the most important determinant of male fertility.
In the most comprehensive study of its kind, researchers from a National Institutes of Health study group reported that a man's ability to procreate is greatly influenced by the shape and appearance of his sperm. Writing in the Nov. 8 issue of The New England Journal of Medicine, the group recommended that sperm appearance, known as morphology, be used to assess male fertility along with sperm count and movement.
The National Cooperative Reproductive Medicine Network also found current standards for evaluating semen to be misleading. They proposed a different measure, which would create a "gray area" of male fertility. Men now considered infertile under the World Health Organization (WHO) guidelines adopted half a century ago might be considered borderline under the proposed criteria.
Lead researcher David S. Guzick, MD, PhD, of the University of Rochester Medical Center, tells WebMD the study findings demonstrate what many doctors have long suspected: Male infertility is not as clear-cut as current laboratory guidelines suggest.
"The current standards treat sperm quality like a light switch. If it falls above a certain value it is normal, and if it is below that value it is abnormal -- like turning a light off and on," Guzick says. "But we found that there is a big overlap and that male infertility is really a biological continuum. Focusing infertility efforts on the man who is in this gray area may be a waste of time and money."
About one out of six couples experience problems conceiving, and in 30% to 40% of cases the male is considered to be infertile. In this study, Guzick and colleagues analyzed semen samples from both fertile and infertile couples in which tests on the female showed no abnormalities.