Among 394 severely malnourished children in Ethiopian hospitals, 15.5% developed comorbid pneumonia or diarrhea. The strongest predictor was very low perceived birth weight, which increased comorbidity odds seven-fold (AOR = 7.11). Children with poor dietary diversity consuming fewer than five food groups faced double the risk, while those with single mothers showed three times higher odds of complications. These findings illuminate the cascading health vulnerabilities that begin before birth and compound throughout early childhood. Low birth weight, often reflecting maternal malnutrition or pregnancy complications, appears to create lasting immune deficiencies that make children more susceptible to life-threatening infections when already struggling with severe malnutrition. The dietary diversity connection underscores how micronutrient deficiencies beyond caloric insufficiency drive disease susceptibility. For global health practitioners, this research reinforces that preventing severe malnutrition requires interventions starting in pregnancy and extending through comprehensive feeding programs that emphasize food variety, not just quantity. However, this preprint awaits peer review, and the cross-sectional design cannot establish causation. The reliance on perceived rather than measured birth weight also limits precision of this key finding.