What drives inequality in modern family planning use among urban women residents? A cross-sectional analysis using the inequality of opportunity framework in Uganda's secondary cities.

Introduction: Modern family planning (mFP) use is vital for improving women's health and rights. Yet, within urban areas, growing inequalities in service access remain poorly understood. This study applies the inequality of opportunity framework to examine individual and contextual drivers of mFP use in Uganda's emerging secondary cities. Methods: We analysed cross-sectional survey data collected in November-December 2021 from 1023 women aged 15-49 in Iganga Municipality and Jinja City, Central-Eastern Uganda. Multivariable logistic regression was used to examine associations between mFP use and individual-level predictors. The Shapley decomposition method was applied to a weighted logistic regression model to quantify the proportion of inequality attributable to unfair circumstances versus fair differences in effort (sexual activity). Results: mFP prevalence was 45.6% (95% CI 41.8% to 49.4%), with 63% of users relying on long-acting reversible methods. The Shapley analysis findings indicated that 37.8% of the variation in predicted mFP use was explained by observed predictors. Of this, 90% was due to unfair circumstances: age (17%), parity (16%), employment (10%), religion (9.5%), authority (9%), place of residence (9%), wealth position (8%), education (7%) and marital status (5%). mFP use declined with increasing age but rose with parity, with the highest likelihood observed among women aged 20-30 years with three or more children. While mFP use generally increased with wealth and employment, among poor women, those who were employed, lived in non-slum areas or were educated were paradoxically less likely to use mFP. Conclusion: Inequality in mFP use in Uganda's secondary cities stems from structural and demographic disadvantages beyond women's control. Poorer women who were educated, employed or in non-slum areas were still less likely to use mFP, suggesting how pro-poor efforts may miss marginalised subgroups within advantaged categories. Addressing these gaps requires inclusive, intersectional strategies that reflect urban inequality and promote equitable access.