Feasibility and diagnostic accuracy of neonatal anthropometric measurements in identifying low birthweight and preterm infants in Africa: a systematic review and meta-analysis.

Background: Complications of prematurity are the leading cause of under-5 mortality globally and 80% of newborn deaths are of low birth weight (LBW) babies. Early identification of LBW and preterm infants is crucial to initiate timely interventions.

Objective: To evaluate the feasibility and diagnostic accuracy of alternative neonatal anthropometric measurements in identifying LBW and preterm infants in Africa.

Methods: In this systematic review and meta-analysis, we evaluated the diagnostic performance of infant foot length, mid-upper arm circumference (MUAC), head and chest circumferences against birth weight and gestational age. Pooled correlation between the index and the reference methods was estimated. Multiple anthropometric thresholds were considered in estimating the pooled sensitivity, specificity and area under receiver operating characteristic curve (AUC).

Results: 21 studies from 8 African countries met the inclusion criteria. Correlation coefficients with birth weight were 0.79 (95% CI 0.70 to 0.85) for chest circumference, 0.71 (95% CI 0.62 to 0.78) for MUAC and 0.66 (95% CI 0.59 to 0.73) for foot length. Foot length measured by rigid ruler showed a higher correlation than tape measurement. Chest circumference with 28.8 cm cut-off detects LBW babies with AUC value of 0.92 (95% CI 0.71 to 0.97). Foot length identified preterm infants, with 82% sensitivity, 89% specificity and AUC of 0.91 (95% CI 0.69 to 0.98) at a 7.2 cm optimal cut-off point. MUAC had an AUC of 0.83 (95% CI 0.47 to 0.95) for preterm detection. In identifying LBW babies, foot length and MUAC have AUC values of 0.89 (95% CI 0.70 to 0.96) and 0.91 (95% CI 0.73 to 0.97) at 7.3 cm and 9.8 cm optimal cut-off points, respectively. Foot length and MUAC are relatively simple and minimise the risk of exposing infants to cold.

Conclusion: Newborn foot length, MUAC, head and chest circumferences have comparable diagnostic accuracy in identifying LBW and preterm babies. Using foot length and MUAC in low-resource settings are the most feasible proxy measures for screening where weighing scales are not available.

Prospero registration number: CRD42023454497.