SAN DIEGO, Calif. -- Fertility researchers at the University at Buffalo School of Medicine and Biomedical Sciences have found a link between specific clinical pregnancies and very low levels of two sperm abnormalities.
The two abnormalities -- premature chromosomal decondensation and premature acrosome reaction, which are overlooked in a standard semen analysis -- had never been linked to low pregnancy rates, said Lani J. Burkman, Ph.D., UB assistant professor of gynecology and obstetrics, and urology, and head of the Andrology Section of the UB Department of Gynecology-Obstetrics.
By analyzing hundreds of semen samples and comparing them with subsequent pregnancies in the couples studied, Burkman and colleagues determined that samples showing more than 14 percent premature chromosomal decondensation or more than 7 percent premature acrosome reactions had only a slim chance of leading to a pregnancy.
"We were surprised to see that these two factors related to pregnancy so clearly," said Burkman, lead researcher on the study. "This is a new finding, and it's impressive because the test is so simple."
Burkman will present results of the study today (June 2) at the meeting of the American Urology Association.
The acrosome is a enzyme-filled cap covering half the sperm head. Just before fertilization, enzymes from the acrosome, activated at the proper time, soften the egg's covering, or zona, allowing the sperm head with its genetic material to fertilize the egg. If the enzymes are released too soon, a process called premature acrosome reaction, the sperm is rendered useless.
Premature chromosomal decondensation refers to the untimely unraveling of the sperm's tightly packed genetic cargo. If this begins before the sperm has penetrated the egg, the sperm head swells and fertilization becomes impossible.