Delaying motherhood is known to cause problems for both mothers and their children. Now, we have further details on this topic. In an article published in PNAS (“Mitochondrial DNA (mtDNA) diseases frequency”,  doi 10.1073/pnas.1409328111), it was shown that the children of older mothers (over 38-years-old), in addition to an increased risk of chromosome alterations in their cellular DNA, may also have alterations in their mitochondrial DNA, which could have adverse effects in the mitochondria, since these mitochondrial alterations are known to cause serious diseases. The study concluded that there are positive association between the number of child heteroplasmies and maternal age at fertilization.