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Outcome studies of low birth weight infants published in the last decade: a metaanalysis
G P Aylward1, S I Pfeiffer, A Wright
1Department of Pediatrics, Southern Illinois University School of Medicine, Springfield 62794-9230.
Insights
Low birth weight infants show slightly lower average IQ/DQ scores compared to controls. However, the clinical significance of this difference is uncertain, with no variations found among different low birth weight subgroups.
Area of Science:
- Neonatal research
- Developmental pediatrics
- Public health
Background:
- Low birth weight (LBW) is a significant global health concern.
- Infants born with low birth weight face potential developmental challenges.
- Previous research has yielded varied findings on cognitive outcomes for LBW infants.
Purpose of the Study:
- To conduct a meta-analysis and methods review of studies on low birth weight infant outcomes.
- To analyze cognitive development (IQ/DQ) in low birth weight, very low birth weight, and extremely low birth weight infants.
- To identify and categorize methodological issues in existing research.
Main Methods:
- Meta-analysis and methods review of 80 studies published in the last decade.
- Inclusion of studies focusing on infants with birth weights ≤2500 gm (LBW), ≤1500 gm (VLBW), and ≤1000 gm (ELBW).
- Categorization of study problems into subject/methods, environmental factors, and outcome measurement.
Main Results:
- The average intelligence quotient/developmental quotient (IQ/DQ) for all low birth weight groups was 97.77, compared to 103.78 for control subjects (statistically significant, but potentially not clinically significant).
- No significant differences in mean IQ/DQ scores were observed among the low birth weight, very low birth weight, and extremely low birth weight subgroups.
- Categorical data analysis revealed statistically significant differences between LBW groups and controls, and among the subgroups, though interpretation is limited by diverse outcome criteria.
Conclusions:
- While statistically significant differences in cognitive scores exist between low birth weight infants and controls, the clinical significance is questionable.
- Developmental outcomes, specifically IQ/DQ, do not appear to differ significantly across varying degrees of low birth weight (LBW, VLBW, ELBW).
- Methodological inconsistencies and diverse outcome measures across studies complicate definitive conclusions from categorical data analyses.
Abstract:
We conducted a metaanalysis and methods review of 80 studies, published in the last decade, that explored the outcome of low birth weight infants; 27% involved infants whose birth weights were less than or equal to 2500 gm (low birth weight), 44% less than or equal to 1500 gm (very low birth weight), and 29% less than or equal to 1000 gm (extremely low birth weight). Problems found in these studies were grouped into three categories: subject and methods issues, environmental factors, and outcome measurement. The combined average intelligence quotient/developmental quotient (IQ/DQ) of all low birth weight groups was 97.77 (SD 6.19); for control subjects the mean IQ/DQ was 103.78 (SD 8.16). This difference was statistically significant but perhaps not clinically significant. No differences in mean IQ/DQ scores were found among the low birth weight, very low birth weight, and extremely low birth weight subgroups. Statistically significant differences among all groups and control subjects were found when categoric data were analyzed, as were differences among the three subgroups; however, the variety of outcome criteria makes interpretation of the categoric analyses difficult.