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New Recommendations to Assess Male Fertility Question
(11/20/2011) by NIH NEWS RELEASE
New recommendations from an NICHD study question current
standards for determining whether a semen sample is normal
or abnormal. Under the new recommendations, many men
formerly considered fertile may, in fact, have difficulty
fathering a child. Conversely, men who fall below the
threshold of the current standards, may be capable of
fathering a child.
The study, based on the most comprehensive analysis of its
kind, was conducted by researchers in the NICHD-sponsored
National Cooperative Reproductive Medicine Network, and
appears in the November 8 "New England Journal of
Medicine".
"These recommendations provide a more reliable means for
estimating the likelihood of a man's fertility," said Duane
Alexander, M.D., director of the National Institute of
Child Health and Human Development. "This will prove a
valuable tool for specialists treating couples with
unexplained infertility, allowing them to make their best
judgment on whether it would be more helpful to focus on
treatment for the man or the woman."
Current standards for estimating the fertility of semen
samples have been established by the World Health
Organization (WHO). In the article, the authors noted that
two other studies questioned the accuracy of the WHO
reference values. Semen analysis is the routine method for
estimating a man's chances for establishing a pregnancy.
The method consists of counting the number of sperm per
milliliter, determining the percentage of sperm that are
moving (sperm motility) and assessing the sperm's shape
(morphology). Normal sperm are oval shaped.
About 1 in 6 couples have difficulty conceiving a child,
said the study's first author, David Guzick, M.D., chairman
of Obstetrics and Gynecology at the University of Rochester
Medical Center. In 30 to 40 percent of these couples, the
males are infertile.
The research team analyzed semen samples from 765 men in
infertile couples and 696 samples from men in fertile
couples from 9 locations around the country. The men
ranged from 20 to 55 years of age. The men were considered
fertile if their partner had conceived within the last two
years.
According to the WHO criteria, normal semen contains 20
million sperm per milliliter, with at least 50 percent
motility. Dr. Guzick and his coworkers found that men
were most likely to be fertile if their semen had more than
48 million sperm per milliliter, more than 63 percent
motility, and more than 12 percent having a normal
appearance. The researchers also identified a "gray zone,"
in which men had borderline fertility, but yet could still
establish a pregnancy. Samples from this group had sperm
counts between 13.5 and 48 million sperm per milliliter,
more than 63 percent motility, and had more than 12 percent
of sperm with a normal shape. Finally, the researchers
found that men were most likely to be infertile if their
samples contained fewer than 13.5 million sperm per
milliliter, less than 32 percent motility, and contained
fewer than 9 percent of sperm with a normal shape.
"Every treatment for infertility depends upon first
establishing what's normal and abnormal," Dr. Guzick said.
"Up until now, we've just been using guidelines without
rigorously testing them. We hope specialists will use these
revisions in their counseling of infertile couples and in
tailoring treatments to individual patient circumstances."
The NICHD is part of the National Institutes of Health, the
biomedical research arm of the Federal government. The
Institute sponsors research on development before and after
birth; maternal, child, and family health; reproductive
biology and population issues; and medical rehabilitation.
NICHD publications, as well as information about the
Institute, are available from the NICHD website,
http://www.nichd.nih.gov, or from the NICHD Clearinghouse,
1-800-370-2943; E-mail NICHDClearinghouse@mail.nih.gov. This article appears in the following topics:
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