Sperm function may have an upper age limit, according to researchers at the Dokkyo Medical University in Koshigaya, Japan. They found that infertility in older couples may have an important male factor that eludes common semen analysis.

In an abstract presented at the Men’s Health World Congress, Hiroshi Okada, MD, and colleagues evaluated sperm’s ability to activate an egg.  The study included men with normal semen analyses, including normal sperm concentration, sperm motility and form.  Using intracytoplasmic sperm injection (ICSI), their sperm were instilled in mouse oocytes.  The activation rates ranged from 68% and 90% in all age groups (ages 20-60 years) but declined significantly after 35 years of age.

While previous studies have shown a decrease in sperm motility with aging, this study shows a potential new factor to consider in the workup of older infertile couples.

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