Background: Many studies have separately addressed the associations of informal caregiving with coresidence, a caregiver's work status, and health conditions, but not jointly. We examined how their parents' need for care affects middle-aged women's lifestyle and psychological distress, considering the potential simultaneity of decisions on caregiving and living adjustments.; Methods: We used 22,305 observations of 7037 female participants (aged 54-67 years) from a nationwide longitudinal survey in Japan conducted during 2009 and 2013.