While risk of nondisjunction type issues increase with maternity age, probably the bigger risk is with paternal age and the steady increase of mutations (http://www.ncbi.nlm.nih.gov/pubmed/22914163). So really we should be freezing sperm. Personally I would have done it myself a couple years ago (i.e. when this paper came out 😛) if I had the financial resources to do so, as well as put in some safeguards against them using the wrong sample.