The present study examined whether the experience of the arrest or incarceration of a mother's partner before a child reached 14 years of age was associated with use of cannabis in early adulthood and, if so, whether this association was confounded or mediated by other factors.

Data were from the Mater Hospital University of Queensland Study of Pregnancy, a prospective birth cohort study in Brisbane, Australia. The history of partner arrest and incarceration was reported by mothers at the 14 year follow up. Mothers were divided into four groups: mothers whose partner had no history of arrest or incarceration, mothers reporting partner arrest, mothers reporting partner incarceration, and unpartnered mothers. Young adults' cannabis use was assessed at 21 years. Other covariates were prospectively measured between birth and 14 years.

After controlling for potential confounding and mediating factors, frequent use of cannabis at age 21 was more likely among young adults with a history of maternal partner arrest (odds ratio=2.3; 95% confidence interval: 1.4-3.8). There was no significant association between maternal partner incarceration or single motherhood, and cannabis use at age 21.

Arrest of the mother's partner before the child is 14 is associated with that child's increased cannabis use at age 21 but this does not appear to be the case for children whose fathers have been imprisoned. It appears that for children whose fathers have been arrested, the father's ongoing presence in the family may result in worse outcomes for the child, including an increased risk of cannabis use in young adulthood.