Conclusions
Our findings suggest that delaying the first birth from adolescence to adulthood may improve birth outcomes and reduce mortality of neonates. Babies born to younger mothers, who are smaller at birth, may experience catch-up growth, reducing some of the anthropometric disparities by 6 months of age.Babies born to adolescent mothers on average had lower weight at birth and lower weight, shorter length, lower mid-upper arm circumference, lower Length-for-Age Z Score, Weight-for-Age Z Score and Weight-for-Height Z Score at enrolment compared with babies of adult mothers.Infants born to adolescent mothers had similar growth outcomes to infants born to adult mothers, suggesting that catch-up growth reduces some of the anthropometric disparities in early childhood.Infants born to adolescent mothers had twice the risk of mortality by 6 months of age compared with infants of adult mothers.Delaying childbirth from adolescence to adulthood can improve birth outcomes and reduce mortality of neonates.Whereas the effect of biases on the point estimate for infant mortality is substantial, under all scenarios correcting for selection bias and unmeasured confounding, the odds of mortality in 6 months was higher for babies born to adolescent mothers compared with adult mothers. Changes in estimates in quantitative bias analysis show the importance of considering the role of biases in examining effects of interest.