BackgroundLiterature on outcomes of children in out-of-home care (OHC) is extensive. However, less is known regarding associations of such placements with parental mental health disorders (MHD). ObjectiveThis study investigated changes in hospitalization rates due to MHD among parents, four years before and after placement of their child in OHC. Participants and settingWe used data on 4067 members (Generation 1) of the RELINK53 cohort (individuals born and living in Sweden in 1953) and their 5373 children (Generation 2) in OHC. MethodsUsing random effects regression models, associations between OHC and MHD were examined separately for fathers and mothers. Nested models were tested exploring associations with parent and child/placement-related factors. Marginal effects were computed to assess mean rates of hospitalization annually. ResultsOverall, mothers had higher mean hospitalization rates than fathers. Compared to the year of placement, hospitalization rates were significantly lower in the four years before placement for mothers (9.9 %, 9.5 %, 10.5 %, 12.1 %, respectively) and fathers (5.9 %, 7.6 %, 8 %, 9.8 %, respectively). Mothers showed highest hospitalization rates at the year of placement (26.6 %), while fathers, one year after placement (13.4 %). Hospitalization rates declined significantly directly after placement among mothers, but an unclear and non-significant pattern of results was found among fathers. ConclusionsMost parents have higher hospitalization rates at and directly after placement. Potential hypotheses underlying these findings are discussed, including psychosocial gender differences and opportunities to seek care as means of reunification. There is an urgency to develop strategies to better support these parents throughout the process.