Adolescent Adolescent Maternal Age and Preterm Birth at a Community District Hospital: The Mediating Role of Antenatal Care Attendance

Background and objectives: Maternal age (MA) is associated with preterm birth (PTB), but whether age independently predicts this risk after accounting for social and clinical factors remains unclear. We assessed whether adolescent maternal age (?19 years) independently predicts PTB and gestational age (GA) at delivery in a Ghanaian district hospital population, and identified modifiable factors accounting for any observed association. Methods: This retrospective cohort study analysed singleton, live, spontaneous vaginal births at a district hospital in Ghana (2018-2023; n=2,343 after exclusions). Bivariable (Mantel-Haenszel) and multivariable logistic (PTB) and linear (GA) regression analyses examined associations between MA, ANC attendance, and outcomes, supplemented by diagnostic, sensitivity, and mediation analyses. Results: Adolescents had markedly higher unadjusted odds of PTB than older women (crude OR=2.30, 95% CI 1.63-3.26; p<0.001), sustained after adjustment (adjusted OR 2.20-2.44). After multivariable adjustment, adolescent age was independently associated with neither PTB (adjusted OR=1.21, 95% CI 0.56-2.60, p=0.62) nor GA (coefficient=-0.15, p=0.34). ANC attendance was the strongest independent protective factor in both models (PTB: OR=0.79 per visit; GA: coefficient=0.10; both p<0.001). Higher education was independently associated with both shorter GA and higher PTB odds. Mediation analysis was consistent with a partially mediated pathway from adolescent age through reduced ANC attendance to shorter GA (indirect effect=-0.065 weeks, bootstrap 95% CI -0.128 to -0.008), despite non-significant total and direct effects. Diagnostics supported the robustness of the ANC and education associations; a sensitivity analysis excluding haemoglobin retained a larger sample (n=1,677) in which adolescent age was significantly associated with shorter GA (coefficient=-0.31, p=0.01), suggesting the null finding partly reflects reduced power. Conclusions: Adolescent maternal age carries a substantially elevated crude PTB risk not independently explained by age itself, but consistent with partial mediation through reduced ANC attendance. Strengthening ANC access for adolescents is the most actionable intervention target.