Most studies have looked at neurodevelopmental and psychopathological outcomes. Some investigators have looked at the newborns of mothers who report stress during pregnancy and found a poorer performance on the Neonatal Behavioural Assessment Scale relative to newborns of mothers who do not report stress during pregnancy [30], showing that adverse behavioural outcomes are observable from the very beginning. Studies of infants and toddlers have shown them to have a more difficult temperament [[10], [31]], sleep problems [32], and lower cognitive performance and increased fearfulness [17] associated with higher maternal stress during pregnancy.