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Early postnatal growth of low birthweight infants in the WIC program
1Biology Department, Morningside College, Sioux City, Iowa 51106-1751, USA. mayr@morningside.edu
Insights
Low birthweight infants in the WIC program showed varied growth. Term and very preterm infants met growth standards, while moderately preterm and term low birthweight infants exhibited catch-up growth.
Area of Science:
- Pediatrics
- Neonatology
- Nutritional Science
Background:
- Early postnatal growth is critical for infant development.
- Low birthweight (LBW) infants face unique growth challenges.
- The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) supports vulnerable populations.
Purpose of the Study:
- To analyze early postnatal growth patterns in LBW infants within the WIC program.
- To compare growth trajectories across different neonatal classifications.
- To investigate the impact of neonatal body proportions on postnatal growth in term LBW infants.
Main Methods:
- Infants were categorized into four groups: term normal birthweight (NBW), term LBW, moderately preterm LBW, and very preterm LBW.
- Weight and length z-scores were tracked at 8, 12, and 18 months.
- Term LBW infants were further classified by ponderal index (PI) at birth (low PI vs. proportionate PI) to assess intrauterine growth restriction (IUGR).
Main Results:
- Term NBW and very preterm LBW infants generally met national reference averages for weight and length.
- Term LBW and moderately preterm infants were consistently smaller and shorter than other groups.
- Evidence of catch-up growth was observed in term LBW and moderately preterm infants.
- Infants with asymmetric IUGR (low PI) showed continued improvement in z-scores, while those with symmetric IUGR (proportionate PI) remained smaller.
Conclusions:
- Neonatal status significantly influences early postnatal growth trajectories.
- WIC-enrolled term LBW and moderately preterm infants demonstrate catch-up growth potential.
- Asymmetric intrauterine growth restriction may have a different impact on postnatal growth compared to symmetric restriction.
Abstract:
Patterns of early postnatal growth were analyzed among low birthweight infants enrolled in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Infants were divided into four groups according to their neonatal status: (1) term, normal birthweight (NBW); (2) term, low birthweight (LBW); (3) moderately preterm LBW; and (4) very preterm LBW. Comparison of mean weight and length z-scores indicated that term NBW and very preterm LBW infants were at or near the national reference averages at 8, 12, and 18 months. Term LBW and moderately preterm infants were lighter and shorter than the other two study groups at each visit. Term LBW and moderately preterm infants displayed evidence of catch-up growth during the study period. Catch-up growth was defined as a decrease in the percentage of infants below the 10th percentile for weight. The effect of neonatal body proportions on postnatal growth was investigated in term LBW infants. The infants were divided into two groups based on their ponderal index (PI) at birth (low PI and proportionate PI). Comparison of weight and length z-scores indicated that both groups of term LBW infants improved in z-scores between birth and the first visit (approximately 8 months). However, infants with evidence of asymmetric intrauterine growth restriction (low PI) continued to improve in weight and length z-scores, whereas those with symmetric growth restriction (proportionate PI) remained lighter and shorter.