Abstract
BACKGROUND: Across generations, girls' early marriage recurs in high-risk groups; however there is poor understanding of how behavior and biology interact in this context. We hypothesized an intergenerational cycle of risk, linking early marriage, preterm birth, and school dropout, and evaluated evidence for specific components of this cycle in low-/middle-income countries. METHODS: We conducted a systematized review, searching articles published from 2000 to 2025. We tested four hypotheses. H1: early marriage is associated with preterm birth; H2: preterm birth is associated with low educational attainment; H3: school dropout is associated with early marriage. Hypothesis-specific search terms and eligibility criteria were applied. We also tested hypothesis H4: preterm birth is associated with reduced cognitive function, by evaluating systematic reviews of research from any setting. RESULTS: We identified 184 empirical articles for H1-H3, with 26 satisfying the criteria for full review, and 5 systematic reviews for H4. The available evidence supported H1 and H3, but was weak for H2. For H3, studies indicated contrasting directions of association. The systematic reviews demonstrated evidence supporting H4. The majority of empirical studies reviewed had a low risk of bias. CONCLUSIONS: An intergenerational cycle of risk linking early marriage, preterm delivery and low educational attainment is plausible, involving both behavioral pathways (e.g., school dropout and early marriage) and biological mechanisms (e.g., preterm birth and cognitive function). Few studies have investigated the prospective associations of preterm birth with school outcomes, or school dropout with early marriage, in low- and middle-income countries.