Women's lives have dramatically changed in recent decades as evidenced by trends in educational attainment, employment outside the home, income, and other socioeconomic factors. Self-reported health in 18-70 year old women has been reported to be significantly lower than in men. In Sweden, the 2005 National Public Health Report showed that stressful work environments have become more common, especially for women. The purpose of the study was to monitor trends in well-being and perceived mental stress in the populations of 38- and 50-year-old women and to examine associations with socioeconomic position (SEP). In 1980, 2004, and 2017, population-based samples of 38- and 50-year old women were recruited into the Prospective Population Study of Women in Gothenburg (PPSWG), Sweden. This population-based study included participants from selected birth cohorts to participate in health examinations, at similar ages and with similar protocols on each occasion. Birth cohort comparisons between three representative samples of 38- and 50-year-old women. Well-being (scale 1-7) and perceived mental stress (scale 1-6) based on questionnaires were the main outcomes studied in relation to time. Socioeconomic position (SEP) based on socio-occupational group, i.e. occupational and educational level combined, were examined as correlates of well-being and mental stress at different points in time. Perception of good well-being increased in generations of 50-year-old women between 1980 to 2016, but no significant time trends were seen in 38-year-old women. Perception of high mental stress increased between 1980 and 2016, for both 38-and 50-year-old women. Belonging to a low socio-occupational group was associated with lower perceived well-being in 1980 but not in 2016. Belonging to a low socio-occupational group was not associated with perceived mental stress at any examination. Contemporary women of today have generally higher perceptions of well-being but also higher mental stress regardless of belonging to low or high socio-occupational group. Associations between poor well-being and belonging to a low socio-occupational group that were observed in 1980 and 2004 were not observed in 2016. The Prospective Population Study of Women in Gothenburg, Sweden was approved by the ethics committee of University of Gothenburg (Dnr 65-80; Ö564-03; 258-16). The studies comply with the Declaration of Helsinki and informed consent has been obtained from the subjects.