Mothers, money, and multi-partner fertility: understanding economic outcomes in midlife

his study examines how mothers’ childbearing and relationship histories, specifically, whether they have children with multiple partners (multi-partner fertility, or MPF), are associated with long-term economic outcomes. Drawing on life course and human capital theories, we explore whether MPF is a marker of prior disadvantage and whether it independently contributes to sustained economic hardship. Despite increasing attention to family complexity, few studies have evaluated how MPF relates to mothers’ economic trajectories into midlife. This study addresses that gap by using high-quality panel data and quasi-experimental inference methods to assess whether MPF has long-term implications for income and wealth. We use data from 24 waves of the National Longitudinal Survey of Youth 1979 (NLSY79) to follow a nationally representative cohort of U.S. women into midlife (N = 2,136; ages 45–53 in 2010). We estimate a series of inverse probability of treatment (IPT) weights based on early life characteristics to adjust for potential selection into MPF. Weighted OLS regressions are then used to estimate the association between MPF and two primary outcomes, mother’s personal income and household wealth, measured in midlife. We test three core hypotheses: (1) Early life disadvantage is associated with a higher likelihood of MPF; (2) MPF is associated with less favorable economic trajectories through young adulthood and midlife; and (3) MPF independently predicts lower income and wealth at midlife, even after accounting for selection and life course variables. Findings diverge for our two focal outcomes. MPF is not significantly associated with income at midlife, suggesting that MPF women remain economically active and resilient in terms of earnings. However, MPF is significantly associated with lower wealth accumulation, even after extensive adjustment for early disadvantage and adult socioeconomic characteristics. On average, MPF mothers hold less than one-sixth the wealth of SPF mothers by midlife. This wealth gap appears to reflect not only early life disadvantage and unstable adult trajectories, but also structural barriers to building wealth in complex family systems. On balance, these findings suggest that MPF may reflect adaptive decision-making among economically marginalized women, who prioritize immediate income over long- term wealth. Yet, the caregiving demands, resource fragmentation, and relational instability associated with MPF appear to constrain wealth-building in enduring ways. These results offer new insight into how family complexity contributes to economic stratification and suggest that even when mothers remain attached to the labor market, wealth gaps may persist. Policy efforts aimed at improving the long-term financial stability of families with MPF should address the structural and relational barriers that limit opportunities to save and accumulate assets over time.