BackgroundThe impact of a child's cancer diagnosis on subsequent maternal physical health is unclear.MethodsWe identified all Ontario children diagnosed less than 18 years with cancer between 1992 and 2017. Linkage to administrative databases identified mothers who were matched to population controls. We identified physical health conditions, acute healthcare use, and preventive healthcare use through validated algorithms using healthcare data, and compared them between exposed (child with cancer) and unexposed mothers. Predictors of health outcomes were assessed among exposed mothers.ResultsWe identified 5311 exposed mothers and 19,516 matched unexposed mothers. For exposed mothers, median age at last follow‐up was 48 years, (interquartile range: 42–53). Exposed mothers had an increased risk of cancer (hazard ratio [HR] 1.2, 95% confidence interval [95% CI]: 1.0–1.5, p = .03), but not of any other adverse physical outcomes or of increased acute healthcare use. Exposed mothers were more likely to receive influenza vaccinations (odds ratio 1.4, 95% CI: 1.3–1.5, p < .0001), and underwent cancer screening at the same rate as unexposed mothers. Among exposed mothers, bereavement was associated with a subsequent increased risk of cancer (HR 1.7, 95% CI: 1.2–2.5, p = .004) and death (HR 2.2, 95% CI: 1.2–4.1, p = .01).ConclusionMothers of children with cancer are at increased risk of developing cancer, but not of other adverse physical health outcomes, and were equally or more likely to be adherent to preventive healthcare practices. Bereaved mothers were at increased risk of subsequent cancer and death. Interventions targeting specific subpopulations of mothers of children with cancer or focused on screening for specific cancers may be warranted.