Personality and fertility dynamics in Norway across four decades – Findings from the HUNT survey

In recent years, Western countries have seen unprecedented fertility declines; increasing childlessness, lower fertility levels and a shift in the timing of fertility to increasingly older ages. The reasons behind these changes in reproductive patterns have been insufficiently understood. In an era emphasizing individual autonomy and personal choice in family planning, personality traits could play a significant role in shaping family formation and fertility patterns. To explore this we use personality measures from the Trøndelag Health Study (HUNT) combined with birth records from the Norwegian Population Registry (N = 27,585). We investigated how extraversion and neuroticism related to three measures of fertility (age of a first child, number of children and childlessness) across four decades. Our study finds that extraversion was associated with an earlier age at first birth and a greater number of children ever born. Neuroticism was associated with an earlier age at first birth but fewer children ever born. Associations were generally stronger for men. Extraversion showed no clear time trends, whereas neuroticism has generally become more strongly associated with fertility in younger cohorts.