Statistical analysis methods
REGRESSION
To assess the effect of maternal age on birth and growth outcomes, we used simple and multivariable linear regression. The changes in outcomes between maternal age groups were expressed as beta coefficients.Potential confounders of the association between maternal age and birth and growth outcomes and mortality were selected a priori using a directed acyclic graph (DAG)To determine the effect of maternal age on mortality, we used logistic regression models with estimates expressed as odds ratios (ORs). Complete case analysis was conducted. For 6-month anthropometry measures, which had some missing outcome values (Participant flow diagram. NAITRE, Neonates and Azithromycin, an Innovation in the Treatment of Children in Burkina Faso; MUAC, mid-upper arm circumference; LAZ, Length-for-Age Z Score; WAZ, Weight-for-Age Z Score; WLZ, Weight-for-Length Z ScoreFor the quantitative bias analysis (QBA), we used the 