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The small for gestational age infant: accelerated or delayed pulmonary maturation? Increased or decreased survival?
J E Tyson1, K Kennedy, S Broyles
1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235-9063, USA.
Insights
Small for gestational age (SGA) neonates do not have accelerated pulmonary maturation and a lower risk of respiratory distress syndrome (RDS). Instead, SGA infants face increased risks for RDS, respiratory failure, and death compared to appropriate for gestational age (AGA) infants.
Area of Science:
- Neonatal Medicine
- Perinatal Research
- Pediatric Pulmonology
Background:
- Small for gestational age (SGA) neonates are often presumed to have accelerated pulmonary maturation, leading to a reduced risk of respiratory distress syndrome (RDS).
- This widely held belief has not been rigorously investigated, necessitating a direct comparison between SGA and appropriate for gestational age (AGA) neonates.
Purpose of the Study:
- To compare the risk of RDS, respiratory failure, and mortality in SGA infants versus AGA infants of the same gestational age.
- To critically evaluate the concept of accelerated lung maturation in SGA neonates.
Main Methods:
- Retrospective analysis of neonates born to an indigent population at a large county hospital.
- Multivariate analyses were conducted, controlling for gestational age (GA), race, sex, and congenital anomalies.
- Separate analyses utilized different gestational age estimates and intrauterine growth grids to define SGA status.
Main Results:
- SGA infants did not demonstrate better outcomes than AGA infants across any analysis.
- SGA infants exhibited a significantly increased risk of RDS in some analyses and a markedly higher risk of respiratory failure and death in most analyses.
- The increased risk associated with being SGA was comparable to that of being male or of White race.
Conclusions:
- The prevailing concept that intrauterine growth restriction accelerates lung maturation and improves neonatal outcomes is not supported by this study.
- The findings challenge the established understanding of lung development in SGA infants and call for a critical re-evaluation of this widely accepted notion.
Objective:
Small for gestational age (SGA) neonates have been considered to have accelerated pulmonary maturation and thus a lower risk for respiratory distress syndrome (RDS) than appropriate for gestational age (AGA) neonates. This, however, has not been thoroughly examined. Therefore, we compared SGA infants with AGA infants of the same gestational age (GA) with respect to risk of RDS, respiratory failure, or death.
Population:
An indigent population born in a large county hospital.
Methods:
Multivariate analyses were performed controlling for GA alone or for GA, race, sex, and congenital anomalies. Because the proper method to identify SGA infants is unclear, we performed separate analyses using different GA estimates (obstetric or pediatric) and intrauterine growth grids (hospital-specific grids or grids for a healthy, geographically-defined population).
Results:
SGA infants did not fare better than AGA infants in any analysis. SGA infants had significantly increased risk in some analyses of RDS and in almost all analyses of respiratory failure or death. The risk associated with being SGA was generally comparable to that associated with male sex or White race.
Conclusion:
The concept that intrauterine growth retardation accelerates lung maturation and improves outcome is not supported in comparisons of SGA and AGA infants of the same GA, sex, and race. This widely accepted concept deserves critical re-evaluation.