Socioeconomic and geographic inequalities in modern contraceptive use among adolescent girls aged 15-19 years in Nigeria: a cross-sectional analysis of the 2024 Nigeria Demographic and Health Survey.

OBJECTIVES: We estimated the weighted prevalence of modern contraceptive use among adolescent girls aged 15-19 years in Nigeria, quantified socioeconomic and geographic inequality using the Erreygers corrected concentration index (CI) and identified correlates by marital status. DESIGN: Cross-sectional secondary analysis using the 2024 Nigeria Demographic and Health Survey. SETTING: Nigeria. PARTICIPANTS: 7995 adolescent girls aged 15-19 years. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was current modern contraceptive use. The secondary outcome was the Erreygers corrected CI of socioeconomic inequality. RESULTS: Weighted modern contraceptive prevalence was 2.73% (95% CI 2.29 to 3.18). Among married adolescent and cohabiting adolescent girls (n=1302), education demonstrated a significant dose-response association with modern contraceptive use. Addressing small subgroup sample sizes with Firth's bias correction yielded consistent findings with narrower confidence intervals (eg, higher education: corrected adjusted OR (AOR) 34.33, 95% CI 4.15 to 283.88, vs original AOR 36.42, 95% CI 2.47 to 537.18). Compared with girls with no formal education, the adjusted odds of modern contraceptive use increased progressively among those with primary (AOR 2.58, 95% CI 1.02 to 6.56), secondary (AOR 3.48, 95% CI 1.21 to 9.95) and higher education levels. Among never-married adolescents, geographic region and age were significant independent predictors of modern contraceptive use. Adolescents in the Northwest and Northeast had 79% lower odds of contraceptive use compared with their North Central peers (AOR 0.21, 95% CI 0.08 to 0.51). Additionally, each additional year of age increased the odds of contraceptive use by 75% (AOR 1.75, 95% CI 1.54 to 1.99). Both the standard and Erreygers concentration indices confirmed a significant pro-rich disparity, indicating that the limited use of modern contraceptives is disproportionately concentrated among wealthier adolescents. CONCLUSIONS: Modern contraceptive use among Nigerian adolescent girls remains very low and inequitably distributed. Targeted interventions are urgently needed to improve reproductive health equity.