Outborn Neonates in Nairobi's Public Hospitals: Mortality Burden and Risk Factors

Background Neonatal mortality remains a significant challenge in Sub-Saharan Africa. Outborn neonates - those born outside the admitting hospital - are particularly vulnerable, yet their outcomes remain under-characterized in many low-resource urban settings. This study examines the burden, characteristics, and mortality risk among outborn neonates admitted to public neonatal units in Nairobi, Kenya. Methods We conducted a retrospective cohort study across four high-volume public hospitals in Nairobi County, Kenya. A stratified random sample of 400 outborn neonates admitted between January and December 2023 was reviewed using medical records. To estimate outborn prevalence and the Population Attributable Fraction (PAF) for mortality, we analyzed registry data from 9,021 neonatal admissions with complete outcome and place-of-birth information. Referral distances were calculated using geocoded coordinates of referring and receiving facilities. Multivariable logistic regression identified factors independently associated with inpatient neonatal mortality. Results Outborn neonates accounted for 17% of neonatal admissions, with a mortality rate of 25.6%, double that of inborn (12.5%; crude RR=2.05, p<0.001). The PAF was 15.0% (95% CI: 12.3-17.7%), indicating that one in seven neonatal deaths could be attributed to outborn status. Key factors were significantly associated with increased odds of mortality including; extremely low birth weight (<1000g; AOR=7.8, 95% CI: 2.6, 23), very low birth weight (1000-1499g; AOR= 4.7 95% CI:2.3, 9.7), hypothermia (AOR=2.2, 95% CI: 1.1, 4.5), respiratory distress (AOR=2.1, 95% CI: 1.2, 3.8), and referral distance >12.1 km (AOR=2.6, 95% CI: 1.1, 6.6). Most deaths (68%) occurred within three days of admission. Conclusion Outborn neonates in Nairobi’s public hospitals face substantially higher early mortality, primarily driven by low birth weight, hypothermia, respiratory distress, and longer referral distances. Interventions targeting improved stabilization, timely referral, and early neonatal care are urgently needed. These findings provide actionable evidence to inform policies aimed at reducing neonatal mortality and advancing progress toward SDG 3.2.