Mortality risks of infants with unmeasured birth weight in 33 sub-Saharan African countries: an observational analysis

Background: Although most infants have their birth weights measured, not all newborns have this opportunity, particularly those in low and middle-income countries. This study evaluates neonatal, infant and child mortality among infants who were not weighed at birth compared with peers weighed at birth and to those identified as having low birth weight.

Methods: A cross-sectional observational study of 308 414 African children in 33 countries from the most recent nationally representative Demographic Health Surveys was conducted between 2011 and 2022. Mixed effect Cox regression was used to estimate HRs and 95% CIs, with adjustments made for socioeconomic and proximate determinants of child survival.

Findings: In total, 116 717 (37.84%) infants did not have their birth weight measured. Compared with infants with a measured birth weight, infants without a measured birth weight were at least three and half-times more likely to die within the initial 28 days of life (HR: 3.51; 95% CI 3.18 to 3.88), and approximately two times likely to die by their first birthday (HR: 2.15; 95% CI 2.01 to 2.30) or by their fifth birthday (HR: 1.89; 95% CI 1.78 to 2.00), after adjusting for confounding factors. The disparity in survival rates was consistent between infants who were born at health facilities but were weighed or not weighed at birth. Those unweighed at birth also had a higher risk of death at 28 days of life (HR: 1.76; 95% CI 1.53 to 2.02), by the first birthday (HR: 1.33; 95% CI 1.21 to 1.47) and by the fifth birthday (HR: 1.25; 95% CI 1.14 to 1.37) than infants identified as having low birth weights.

Interpretation: Infants whose birth weight is not measured face a higher mortality risk before age 5 compared with those with measured birth weights. The absence of birth weight measurement may indicate a higher risk profile for newborns and their vulnerability to mortality.