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Updated: Jul 7, 2025
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Postnatal growth in small vulnerable newborns: a longitudinal study of 2 million Brazilians using routine
Aline S Rocha1, Rita de Cássia Ribeiro-Silva2, Juliana F M Silva3
1Center of Data and Knowledge Integration for Health (CIDACS), Oswaldo Cruz Foundation, Salvador, Brazil; School of Nutrition, Federal University of Bahia (UFBA), Salvador, Brazil.
Insights
Preterm infants and those with low birth weight (LBW) or small-for-gestational age (SGA) experience impaired growth. Catch-up growth is delayed, especially for preterm infants, with outcomes worsening for the most vulnerable.
Area of Science:
- Pediatrics
- Neonatology
- Public Health
Background:
- Preterm, low-birth weight (LBW), and small-for-gestational age (SGA) newborns face higher risks of adverse health outcomes, including impaired linear and ponderal growth.
- Understanding growth trajectories in these vulnerable populations is crucial for early intervention and improved long-term health.
- Vulnerability phenotypes in newborns significantly impact subsequent growth and development.
Purpose of the Study:
- To describe the growth trajectories of newborns with preterm, LBW, or SGA phenotypes.
- To estimate catch-up growth during the first five years of life for these vulnerable newborns.
- To analyze growth patterns based on three distinct vulnerability phenotypes.
Main Methods:
- A longitudinal study utilizing linked data from the 100 Million Brazilian Cohort, SINASC, and SISVAN (2011-2017).
- Estimation of length/height-for-age (L/HAZ) and weight-for-age z-score (WAZ) trajectories using linear mixed models for children aged 6-59 months.
- Calculation of growth velocity and definition of catch-up growth (change in z-score > 0.67).
Main Results:
- Analysis included 2,021,998 live births and 8,726,599 observations; 16.7% had at least one vulnerability phenotype.
- Term-born infants showed growth recovery starting at 12 months, while preterm infants experienced delayed L/HAZ recovery (24 months) with lower trajectories.
- Preterm and female infants exhibited slower catch-up growth, particularly those with multiple vulnerability phenotypes (e.g., preterm + SGA + LBW).
Conclusions:
- Children born preterm demonstrate lower L/HAZ and WAZ growth trajectories compared to term-born infants.
- The most vulnerable newborns, particularly those with combined preterm, LBW, and SGA characteristics, face aggravated growth impairments.
- Delayed catch-up growth in preterm infants highlights the need for targeted nutritional and developmental support.
Background:
Preterm, low-birth weight (LBW) and small-for-gestational age (SGA) newborns have a higher frequency of adverse health outcomes, including linear and ponderal growth impairment.
Objective:
To describe the growth trajectories and to estimate catch-up growth during the first 5 y of life of small newborns according to 3 vulnerability phenotypes (preterm, LBW, SGA).
Methods:
Longitudinal study using linked data from the 100 Million Brazilian Cohort baseline, the Brazilian National Live Birth System (SINASC), and the Food and Nutrition Surveillance System (SISVAN) from 2011 to 2017. We estimated the length/height-for-age (L/HAZ) and weight-for-age z-score (WAZ) trajectories from children of 6-59 mo using the linear mixed model for each vulnerable newborn phenotype. Growth velocity for both L/HAZ and WAZ was calculated considering the change (Δ) in the mean z-score between 2 time points. Catch-up growth was defined as a change in z-score > 0.67 at any time during follow-up.
Results:
We analyzed 2,021,998 live born children and 8,726,599 observations. The prevalence of at least one of the vulnerable phenotypes was 16.7% and 0.6% were simultaneously preterm, LBW, and SGA. For those born at term, all phenotypes had a period of growth recovery from 12 mo. For preterm infants, the onset of L/HAZ growth recovery started later at 24 mo and the growth trajectories appear to be lower than those born at term, a condition aggravated among children with the 3 phenotypes. Preterm and female infants seem to experience slower growth recovery than those born at term and males. The catch-up growth occurs at 24-59 mo for males preterm: preterm + AGA + NBW (Δ = 0.80), preterm + AGA + LBW (Δ = 0.88), and preterm + SGA + LBW (Δ = 1.08); and among females: term + SGA + NBW (Δ = 0.69), term + AGA + LBW (Δ = 0.72), term + SGA + LBW (Δ = 0.77), preterm + AGA + LBW (Δ = 0.68), and preterm + SGA + LBW (Δ = 0.83).
Conclusions:
Children born preterm seem to reach L/HAZ and WAZ growth trajectories lower than those attained by children born at term, a condition aggravated among the most vulnerable.
