**7. Long-term disabilities due to advanced maternal age**

Several neurological disorders have been shown to be more frequent in children born from elderly mothers, particularly cerebral palsy [117, 118] and autism spectrum disorders [119]. In terms of learning disabilities, one study found that developmental vulnerability decreases with the mother's age from 15 to 30 years, but starts to increase when the mother is older than 35, this increase being independent from the socioeconomic status [120]. Interestingly, children born from old parents show a poorer neurocognitive performance in childhood [121]. However, environment might make up for the "biological disadvantage", as older parents are usually in a better financial state, are more highly educated, and usually have reached a more stable couple/marriage situation. All this may give them certain emotional maturity and life experience that improves child-rearing abilities. Compared to singletons, twins exhibited higher rates of cerebral palsy and mental retardation and showed more pronounced speech delays, motor development, and behavioural problems. However, the main explaining factor is the higher frequency for preterm delivery that results in low and very low birth weight children [122]. Maternal age contributes by increasing the risk for preterm delivery, but the same way in singletons and twins.

Trisomy 21 is very well known to increase with maternal age due to meiotic non-disjunction errors. More recently, mitochondrial dysfunction and epigenetic changes associated with oocyte ageing can be inherited by the descendant and may predispose also to chromosome segregation errors in grandchildren [123].
