Background <p>The fertility transition in sub-Saharan Africa remains slow; however, the drivers of high fertility in conflict-affected and resource-constrained settings, such as Somalia, remain underexplored.</p> Objective <p>This study analyzed the determinants of a high fertility status, defined as having five or more children born, a threshold associated with high-risk obstetric outcomes, among married women in Somalia.</p> Methods <p>Using data from the 2020 Somali Health and Demographic Survey (SHDS) (<i>N</i> = 40,402), we employed a multilevel logistic regression model. This approach was chosen to account for regional clustering and adjust for the unobserved regional-level heterogeneity inherent in the stratified sampling design.</p> Results <p>This study revealed a distinct socio-demographic gradient. Education acts as a powerful measure of fertility. Women with no education (AOR = 1.29; 95% CI [1.11, 1.50]) and primary education (AOR = 1.44; 95% CI [1.22, 1.70]) had significantly higher odds of high fertility than those with secondary or higher education. Delaying the age of first marriage also significantly reduced this risk. Notably, a systemic “targeting bias” was observed: women not visited by family planning workers were less likely to have high fertility (AOR = 0.77; 95% CI [0.70, 0.85]), suggesting that interventions reactively targeted large families rather than proactively reaching low-parity women. Furthermore, child loss exhibited a powerful dose-response effect, with the odds of high fertility increasing from 1.86 for one death to 8.76 for three or more deaths, supporting the “insurance effect” and replacement motives.</p> Conclusion <p>High fertility in Somalia is driven by educational exclusion, early marriage, and compensatory reproductive behaviors following child loss. To facilitate demographic transition, policies must prioritize female secondary education and shift family planning strategies from reactive targeting to proactive engagement with younger, low-parity women.</p>