Quality of Sperm Declines as Men Age

Andrew Wyrobek, Ph.D. and Brenda Eskenazi, Ph.D.
School of Public Health, University of California Berkeley
P42ES04705

New research suggests that as men age they may have more difficulty fathering children. Like women, the study also suggests that some men who wait to become fathers are slightly more at risk for passing on certain rare diseases.

Obstetricians and gynecologists have long known that as women age their risk of miscarriage increases as does the risk of having children with Down Syndrome or other genetic defects. This study suggests that men too have a ”biological clock,” but one that causes a more gradual change in fertility. As men and women have been postponing parenthood in the past several decades, fatherhood for men aged 35-49 has increased 40% while there has been a decline in births involving men under age 30.

The authors caution that their findings are preliminary and are based on a small number of tests in a small population of men. The study, funded by NIEHS, enlisted 97 men ages 22-80. This research team has previously reported that as men age, their sperm counts decline and their sperm become less active. Increased age of the men was not associated with the same genetic defects seen in older women. For instance there was no increased risk of fathering a child with Down Syndrome, but some older fathers did have an increased risk of having children with dwarfism and according to the published results, ”a small fraction of men are at increased risk for transmitting multiple genetic and chromosomal defects.”

Citation: Wyrobek AJ, Eskenazi B, Young S, Arnheim N, Tiemann-Boege I, Jabs EW, Glaser RL, Pearson FS, Evenson D. Advancing age has differential effects on DNA damage, chromatin integrity, gene mutations, and aneuploidies in sperm. Proc Natl Acad Sci U S A. 2006 Jun 9.