BackgroundParental difficulties, including mental ill health, substance misuse, domestic violence and learning disability have been associated with children entering out-of-home care. There is also evidence that these issues may co-occur within families. Understanding how the co-occurrence of these difficulties is associated with care entry is complex because they may co-occur in the same or different household members and have different impacts on the likelihood of care entry when they occur in mothers, fathers or in single parent households. MethodAdministrative data from local authority children’s services in Wales were linked with demographic data to identify households in which children lived prior to entering care. Linkage to birth data identified biological mothers. Linkage with primary care, emergency department, hospital admissions and substance misuse services data enabled indicators of substance misuse, mental health, assaults in the home, learning disability and neurodivergence in the adults in those households to be identified. A series of multilevel binary logistic regression models were used to explore the odds of a household having one or more children entering care if risk factors were present. These considered the effects of individual risks, and cumulative risk both in individual adults in the household, and across the whole household. The effects of the number of adults, having adults with no risks and the differential impacts of risks in biological mothers, other women or men were also explored. Additional models explored these factors in single adult households. ResultsCumulative risks increased the likelihood of care entry, however this effect disappeared when individual risks were controlled for. The presence of an individual with no risks in the household acted as a protective factor. Overall, the impact of the risks on the odds of care entry was substantially greater if the risks were present in the biological mother than if they occurred in other adults (men or women) in the household. In single adult households risk factors had a much greater impact when they occurred in households headed by women as opposed to men. ConclusionSubstantial differences in the effects of risk factors in female and male adults are apparent and further research is needed to understand why this is occurring to ensure that parents are treated equally in terms of support and statutory intervention regardless of their sex.11Throughout this paper we refer to the “sex” of the parents /adults in households, as opposed to their “gender.” This is because in the analysis we carried out the sex of these individuals was determined by their GP records. We have chosen to use the term “sex,” rather than “gender,” as we believe this data is more likely to reflect their biological sex, rather the gender that the individuals identify as.