The contribution of preterm birth and intrauterine growth restriction to childhood undernutrition in Tanzania

Objectives were to examine the growth patterns of preterm and growth-restricted infants and to evaluate the associations of prematurity and intrauterine growth restriction (IUGR) with risk of stunting, wasting and underweight. Data from a cohort of HIV-negative pregnant women-infant pairs were collected prospectively in Tanzania. Small for gestational age [SGA, birthweight (BW) <10th percentile] was used as proxy for IUGR. Anthropometry was measured monthly until 18 months. Length-for-age (LAZ), weight-for-length (WLZ), and weight-for-age (WAZ) z-scores were calculated using the 2006 World Health Organization (WHO) Child Growth Standards. Stunting, wasting and underweight were defined as binary outcomes using a cut-off of <-2 SD of the respective z-scores. Multivariate Cox proportional hazard models were used to assess the associations between preterm and SGA to time to stunting, wasting and underweight. The study included 6664 singletons. Preterm and appropriate for gestational age (AGA) infants had slightly better nutritional status than term-SGA infants and despite some catch-up growth, preterm-SGA infants had the poorest nutritional status. The gap in LAZ and WAZz-scores among the groups remained similar throughout the follow-up. Compared with term-AGA babies, relative risk (RR) of stunting among preterm-AGA babies was 2.13 (95% confidence interval (CI) 1.93-2.36), RR among term-SGA was 2.21 (95% CI 2.02-2.41) and the highest risk was among the babies who were both preterm and SGA (RR=7.58, 95% CI 5.41-10.64). Similar magnitude of RR of underweight was observed among the three groups. Preterm and SGA infants should be closely monitored for growth failure. Intervention to reduce preterm and SGA birth may lower risk of undernutrition in resource-limited settings.