Effect of parental age on fertilization and pregnancy characteristics in couples treated by intracytoplasmic sperm injection

The purpose of this study was to investigate any influence of maternaland/or paternal age on gamete characteristics and pregnancy outcomes inintracytoplasmic sperm injection (ICSI) cycles. In all, 821 consecutiveICSI cases were analysed retrospectively. While a significant lineardecline in semen volume was detected, no significant differences in theconcentration, motility or morphology of the spermatozoa were found withpaternal ageing. A significant decline in the number of oocytes retrievedand the number of mature oocytes obtained was found with advancing maternalage. An increase in the occurrence of digyny was noted with parentalageing, while no difference in single or bipronuclear fertilization wasfound. Older women had a decreased incidence of single pronucleus formationand an increase in digyny, but no significant difference in the percentageof oocytes that underwent two-pronuclear fertilization was detected withregard to maternal ageing. Pregnancy outcomes were not influenced by theage of the male partner, while a strong negative correlation was found withmaternal ageing. To better analyse male partner ageing as a factoraffecting pregnancy outcome, we analysed a subgroup of patients with afemale partner aged <35 years who underwent ICSI. No paternal influenceon ICSI pregnancy outcome was found in this subgroup of patients. Weconclude that the influence on pregnancy outcome after ICSI is relatedmostly to maternal and not paternal age.