Current literature on the link between fertility and health shows an inverted U-shape relationship between age at first birth and several physical and mental health measures. In particular, very early and very late childbearing are associated with worse outcomes, such as a higher prevalence of chronic diseases and higher risk of depression. However, the pattern of age at childbearing has changed substantially in developed countries, with a consistent postponement of parenthood since 1970s. Moreover, recent evidence suggests that psychological distress in mid-life has increased over time, and understanding its determinants is necessary. Existing studies fail to investigate how postponement of childbearing is associated with mental health outcomes in mid-life. Using data from the British Cohort Studies, we fill this gap in the literature by examining the relationship between age at childbearing and several measures of psychological distress among men and women in their mid-40s, born in 1946, 1958 and 1970.