Objective: To determine whether semen quality has changed in the United States over the last 25 years.
Design: Retrospective review.
Setting: Three U.S. sperm banks, Cryogenic Laboratories, Inc. (Roseville, Minnesota), Idant Laboratories (New York, New York), and California Cryobank, Inc. (Los Angeles, California).
Main outcome measures: Age at sample collection, sperm concentration, volume, motility, and days of abstinence before sample collection were determined for each man. Linear and multiple regression analyses were used to assess changes in these characteristics over time.
Results: Controlling for the effects of age and duration of abstinence, there was a slight but significant increase in mean sperm concentration but no change in either motility or semen volume over the 25-year period. Both sperm motility and semen volume decreased with increasing age at sample collection. Both sperm concentration and semen volume increased as a function of duration of abstinence. There were significant differences in mean (+/- SEM) sperm concentrations (10(6) sperm/mL) and motilities between the different sperm banks with California lowest (72.7 +/- 3.1, 51.4% +/- 1.1%, respectively), Minnesota higher (100.8 +/- 2.9, 56.0%, respectively), and New York highest (131.5 +/- 3.5, 58.2% +/- 0.5%, respectively).
Conclusions: Our data show no decline in sperm counts over a 25-year period in 1,283 men who banked sperm before vasectomy at three distinct geographical sites in the United States.