Peer-reviewed article
Heterogeneous income gradients in early motherhood in Mexico: a population-based multi-method study, 2000-2020.
Serván-Mori E, Zamudio-Sosa A, Esposito L, Sandoval-Moreno G, Jara HX et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study analysed data from 3.05 million Mexican women aged 12-24 across three census years (2000, 2010, 2020) to understand why early motherhood persists in low-income households. The researchers found that early motherhood prevalence declined slightly from 21.46% to 19.31% over 20 years but remained concentrated among disadvantaged populations. Income alone was a weak predictor of early motherhood; instead, the pathways linking poverty to early childbearing operated mainly through reduced schooling and early union formation. The study identified persistent geographic clustering of early motherhood, suggesting unmeasured local factors also play important roles.
Key points
- Early motherhood prevalence in Mexico declined modestly from 21.46% (2000) to 19.31% (2020) but remained concentrated in socioeconomically disadvantaged households
- Household income ranked eighth in feature importance for predicting early motherhood; direct income effects were not statistically significant in dynamic models
- Income showed a non-linear inverse L-shaped association with early motherhood risk, increasing up to approximately Int$1,760 per adult equivalent (2018 PPP), then plateauing
- Schooling lag and early union formation were the primary pathways linking income to early motherhood, rather than income as a direct driver
- Significant spatial clustering persisted after adjustment for individual-level predictors, indicating unmeasured contextual constraints shape early motherhood at municipal level
Limitations
This is an observational study using census data and imputed household income, so causal inferences about income effects cannot be firmly established. The study cannot explain the unmeasured contextual factors and 'place effects' identified in municipal-level analyses, limiting understanding of local mechanisms.
Abstract
Background Early motherhood remains a major public health and equity challenge in low- and middle-income countries, especially in Latin America. While poverty, education, gender norms, and barriers to sexual and reproductive health are well-established determinants, how household income translates into (or fails to translate into) delayed childbearing remains insufficiently understood-particularly in highly unequal settings marked by informality and fragmented social protection. Objective To examine the association between household income and early motherhood in Mexico, and to disentangle direct and indirect socioeconomic pathways linking income to early childbearing. Methods We conducted a population-based, multi-method analysis using harmonised municipal microdata from the 2000, 2010, and 2020 Mexican Population and Housing Censuses (n = 3.05 million women aged 12-24 years, representing 30.6 million individuals). Total household income was imputed using Quantile Random Forests trained on nationally representative income-expenditure surveys. Our analytical strategy combined: (1) machine learning models to identify key correlates and non-linear individual-level patterns of early motherhood; (2) Bayesian spatial models (INLA) to quantify subnational clustering and contextual heterogeneity; and (3) dynamic structural equation modelling to assess direct and lagged relationships among income, schooling-related indicators, union formation, and early motherhood outcomes. Results Early motherhood prevalence declined modestly from 21.46% (2000) to 19.31% (2020) and remained concentrated in socioeconomically disadvantaged households. In individual-level models, marital status, age, household structure, and dependency ratio were the dominant correlates; income ranked eighth in feature importance. Partial dependence plots indicated a non-linear inverse L-shaped association: predicted risk increased up to approximately Int$ 1,760 (2018 PPP) per adult equivalent, then plateaued and declined slightly. Parity-specific models showed that income's predictive relevance weakened with higher parity, with U-shaped patterns at the lowest income levels for second and ≥third births. Municipal analyses revealed persistent spatial clustering after adjustment for key predictors, and residual "place" effects consistent with unmeasured contextual constraints shaping early motherhood. In dynamic models, the direct income-early motherhood path was not statistically significant. Overall patterns were consistent with predominantly indirect linkages operating through schooling- and union-related indicators and reinforcing disadvantage dynamics at the municipal level. Conclusions In Mexico, early motherhood remains strongly shaped by intersecting social and territorial inequalities. Income gradients are modest and appear to operate mainly through schooling lag and union-formation pathways rather than as an isolated driver. Equity-oriented strategies are likely to be most effective when they integrate school retention, prevention of early unions, and youth-friendly sexual and reproductive health services, prioritising municipalities with persistently elevated risk.