There is good evidence that parental psychiatric disorder has a deleterious effect on child development. Rutter has outlined a number of possible reasons for this.1 First, there may be a direct pernicious impact on the child of exposure to the parental disorder. Second, there may be an indirect impact via the effect of the parental disorder on interpersonal behaviour in general and parenting in particular. Finally, the impact may be via third factor variables, such as the social adversity commonly associated with psychiatric disorder, or genetic or constitutional factors. Depression arising in the postnatal period could have an impact on infant development via each of these causal pathways. The infant’s extreme dependency on their caretaker, their sensitivity to interpersonal contacts,2 and the fact that, in the great majority of cases, the mother constitutes the infant’s primary environment in the first postnatal months, make the question of the impact of depression occurring at this time one of particular importance. An account is given below of the evidence implicating postnatal depression in adverse infant outcome. This evidence is then examined in the light of the possible causal frameworks outlined above.

A number of studies have examined the 1 to 2 year old infants of mothers who have had a postnatal depression.3-8 These studies have generally found an association between early maternal depression and adverse cognitive and emotional infant development.