© 2014 Elsevier Ltd. Mothers of a child with intellectual disability (ID) have more psychiatric disorders after the birth of their child than other mothers. However, it is unclear if this is because they have more psychiatric disorders before the birth or if the increase is related to the burden of caring for the child. We aimed to calculate the rate of new psychiatric disorders in mothers after the birth of their eldest child with ID born between 1983 and 2005 and to compare these with rates in women with a child with no ID or autism spectrum disorder (ASD) born during the same period. By linking data from Western Australian population-based registries, we selected women with no psychiatric history who survived the birth of their live-born child (N=277,559) and compared rates of psychiatric disorders for women with a child with ID and women without a child with or ASD. Negative binomial regression with STATA 12 was used for all analyses. Mothers of children with mild-moderate ID of unknown cause had around two to three and a half times the rate of psychiatric disorders of mothers of children without ID or ASD. Mothers of children with Down syndrome and no pre-existing psychiatric disorder showed resilience and had no impairments in their mental health. Interventions and services are needed for mothers of other children with ID to improve their mental health. Further research is implicated to explore the mental health of mothers of children with ID and a pre-existing psychiatric disorder.