To identify patterns of health system-identified early childhood maltreatment by maternal birthplace and child sex, within a multicultural society with universal access to healthcare.

This retrospective population-based cohort study included 1240946 children born in Ontario, Canada, between 2002 and 2012, and followed from birth to age 5 years using administrative data. Modified Poisson regression was used to estimate adjusted rate ratios for maltreatment—physical abuse or neglect—among the children of immigrant vs nonimmigrant mothers. Conditional logistic regression was used to estimate further the odds of maltreatment comparing a daughter vs son of the same mother.

Maltreatment rates were 36% lower (adjusted rate ratio, 0.64; 95% CI, 0.61-0.66) among children of immigrant mothers (10 per 1000) than those of nonimmigrant mothers (16 per 1000). Maltreatment rates were 27%-48% lower among children of maternal immigrant groups relative to that among Canadian-born mothers, except children of Caribbean-born mothers (16 per 1000). No significant differences were seen between daughters and sons in the odds of early childhood health system-identified maltreatment by maternal birthplace.

Health system-identified maltreatment in early childhood is highest among children of Canadian- and Caribbean-born mothers. Maltreatment did not differ between daughters and sons of the same mother. These data may inform strategies aimed at decreasing maltreatment among vulnerable groups.