Mortality and risk factors of small vulnerable newborns in 32 low- and middle-income countries.

Background: In 2022, 2.3 million neonatal deaths occurred globally, the majority of which were in low- and middle-income countries (LMICs). Preterm birth, small for gestational age (SGA), and low birth weight (LBW) are leading causes of neonatal mortality. The Small Vulnerable Newborn (SVN) framework was introduced to unify preterm birth, SGA, and LBW under a single concept. SVNs face significant mortality risks and are predominantly found in LMICs. Understanding the prevalence, mortality risks, and associated factors of SVNs is essential for targeted intervention efforts.

Methods: This study analyzed nationally representative survey data from the Demographic and Health Surveys (DHSs) conducted between 2008 and 2022 in 32 LMICs, covering 197,405 weighted live births among mothers aged 15-49 years. SVN prevalence, neonatal mortality, infant mortality, and associated risk factors were examined using modified Poisson regression and multinomial logistic regression. Population attributable fractions (PAFs) estimated the contribution of modifiable factors.

Results: The overall SVN prevalence was 23.91% across 32 LMICs. Preterm-SGA showed the highest mortality risks compared to term-nonSGA newborns (neonatal: adjusted RR = 17.51 [95% CI, 12.95-23.67]; infant: adjusted RR = 11.86 [95% CI, 9.20-15.29]). Preterm-nonSGA contributed most to overall mortality (neonatal PAF: 11.72%; infant PAF: 8.15%). Risk patterns varied by subtypes: first parity was primary for preterm-nonSGA (PAF: 14.25%), poverty for term-SGA (PAF: 7.95%), while both insufficient antenatal care (< 4 visits) and first parity were major contributors for preterm-SGA (PAF: 22.68% and 20.41%). Adolescent pregnancy showed the strongest association with overall SVNs (adjusted RR = 1.37 [95% CI, 1.33-1.40]).

Conclusions: SVNs remain a significant public health challenge in LMICs, with distinct risk patterns among subtypes suggesting the importance of targeted interventions focusing on antenatal care, socioeconomic factors and adolescent pregnancy prevention.