How Personality Shapes the Timing and Spacing of Fertility: Evidence From Three Countries

How do personality traits influence childbearing behavior, and to what extent can demographic changes in traits explain fertility declines in recent decades? Using harmonized longitudinal data from Australia, the United Kingdom, and western Germany, this study estimates multistate duration models linking the Big Five personality traits to the timing of first, second, and third births. Greater openness to experience is consistently associated with delayed childbearing. Across all three countries, a one-standard-deviation increase in openness is associated with an 11--16\% reduction in the hazard of a first birth—a magnitude comparable to the effect of 1.0--1.5 additional years of schooling. In contrast, greater agreeableness is associated with earlier childbearing, while greater conscientiousness is associated with a lower hazard of a third birth. Because personality is frequently measured after childbearing has begun, we use repeated personality assessments to test whether motherhood affects the measured traits and find no evidence that it does. A decomposition of model-simulated completed fertility indicates that intercohort changes in personality and education account for approximately 9\% of the fertility decline between women born in 1960--1970 and 1980--1990, with education contributing about 2.5 times as much as personality. Personality therefore helps explain why women facing similar circumstances follow different fertility trajectories, but demographic trends in personality traits explain only a small fraction of the aggregate fertility decline.