Trends in pre-existing mental health disorders among parents of infants born in Western Australia from 1990 to 2005

Objective: To determine the prevalence of prior and current mental health disorders in parents, including trends over time. Design: A retrospective population cohort study using de-identified linked health data. Setting: Population of Western Australia. Subjects: All parents of infants born in WA between 1990 and 2005. Main outcome measures: Prevalence of prior mental health disorders in parents by birth year and by parent and child characteristics, including Aboriginality, maternal age, socioeconomic status and diagnostic groups. Results: From 1990 to 2005, there was an increase in prevalence of prior mental health disorders in mothers, from 76 per 1000 births in 1990 to 131 per 1000 births in 2005 (3.7% increase per year in the odds of children being born to mothers with a prior mental health disorder). There was also a 4.7% increase in odds per year in the prevalence of mental health contacts that had taken place in the 12 months before the birth year in mothers. In addition, there was an increase in prevalence of prior mental health disorders in fathers, from 56 per 1000 births in 1990 to 88 per 1000 births in 2005 (3.1% increase in odds per year). The diagnostic group with the highest prevalence in both mothers and fathers was substance-related disorders. Conclusions: From 1990 to 2005, there was an increase in prevalence of parents with a prior history of mental health disorders in WA. General practitioners and mental health workers can play an important role in identifying mental illness and in working with families to offer early intervention, referral and support.