PATERNAL AGE AFFECTS FERTILITY AND PROGENY OUTCOME IN THE BROWN-NORWAY RAT

Objective: To investigate the effects of paternal age on fertility and progeny outcome using the Brown Norway rat model. Design: Controlled prospective study. Setting: McIntyre Animal Centre, McGill University, Montreal, Quebec, Canada. Intervention(s): Brown Norway male rats of increasing age were mated to young Sprague-Dawley females. Main Outcom e Measure(s): Pregnancy outcome was assessed by counting the numbers o f corpora lutea, resorptions, and live fetuses on day 20 of gestation. To evaluate progeny outcome, pups were examined for external malforma tions and weighed daily for 2 months. Result(s): There were no signifi cant changes in the numbers of resorptions, offspring, or in the incid ence of external malformations. However, there was an increase in prei mplantation loss (corpora lutea minus implantation sites) in litters f athered by older males. Furthermore, a significant decrease in the ave rage fetal weight was found with increasing. paternal age. A significa nt increase in neonatal deaths for progeny fathered by older males als o was found. Conclusion(s): These results indicate that the quality of spermatozoa decreases as males age. (Fertil Steril(R) 1998;70: 625-31 . (C) 1998 by American Society for Reproductive Medicine.).