Long-term effects of delayed parenthood

The present study aims to define, characterize and compare the long-term ef fects on offspring of delayed parenthood. Data published so far on this top ic show that maternal and paternal ageing may affect offspring by different mechanisms. Delayed motherhood is characterized by increased probability o f obstetric complications and/or fetal and perinatal problems which, in tur n, may increase the risks of mortality and morbidity in newborns and later life. Furthermore, maternal ageing is distinguished by a decreased ratio of male to female infants and higher odds of conceiving a trisomic child and/ or an individual suffering from mitochondrial DNA disorders. In contrast, d elayed fatherhood is associated with higher risks of conceiving an individu al suffering from new inheritable-mutation disorders. The different pattern of disease in offspring associated with maternal and paternal ageing may b e explained, among other factors, by the fact that (i) oocytes of middle-ag ed women may suffer oxidative stress because their mitochondria produce hig her amounts of reactive oxygen species; (ii) diplotene oocytes and to a les ser extent metaphase I and II oocytes have an efficient DNA repair system w hich is essentially independent of maternal age; and (iii) mitochondria are transmitted to the next generation along the matrilineal line. Moreover, ( i) the activities of antioxidant enzymes within the seminal plasma and sper matozoa from older men may be reduced and so spermatozoa may be more vulner able to mutational changes than spermatozoa from younger men; and (ii) late spermatids, and immature,and mature spermatozoa do not have a DNA repair s ystem.