Related Experiment Videos
Body proportionality and head and length 'sparing' in growth-retarded neonates: a critical reappraisal
M S Kramer1, F H McLean, M Olivier
1Department of Pediatrics, McGill University Faculty of Medicine, Montreal, Quebec, Canada.
Insights
The distinction between proportional and disproportional intrauterine growth retardation is not supported by evidence. Growth-retarded infants show a continuum of disproportionality, not distinct subtypes.
Area of Science:
- Neonatalogy
- Pediatric Growth Studies
- Fetal Development Research
Background:
- Current classifications of intrauterine growth retardation (IUGR) distinguish between "proportional" and "disproportional" types.
- The empirical basis for these distinct subtypes and their varying body proportions has not been well-established.
Purpose of the Study:
- To investigate whether body proportions differ significantly between growth-retarded and non-growth-retarded infants of similar birth weights.
- To determine if proportionality is bimodally distributed among infants with IUGR.
Main Methods:
- Analysis of a large cohort (n=8719) of neonates with reliable gestational age dating.
- Categorization into four groups: non-growth retarded, mild IUGR, moderate IUGR, and severe IUGR.
- Comparison of length, head circumference, and proportionality ratios based on gestational age and birth weight.
Main Results:
- Growth-retarded infants exhibited lower lengths, head circumferences, and proportionality ratios compared to non-growth-retarded infants of the same gestational age.
- Deficits in these measurements increased significantly with the severity of IUGR.
- When compared by birth weight, growth-retarded infants showed slightly greater lengths and head circumferences with increased variability in proportions, but no evidence of bimodality.
Conclusions:
- Proportionality in IUGR infants represents a continuum, with increasing disproportionality correlating with IUGR severity.
- The study challenges the concept of distinct proportional and disproportional IUGR subtypes.
- Despite some "sparing" effects, significant absolute deficits in length and head growth persist in IUGR infants.
Abstract:
Despite the popular current distinction between "proportional" and "disproportional" intrauterine growth retardation, it has never been shown that variation in body proportions is greater among growth-retarded than nongrowth-retarded infants of the same birth weight, nor that proportionality is distributed bimodally among growth-retarded infants. Based on a cohort of 8719 neonates born between 1980 and 1986 of mothers with concordant (+/- 7 days) menstrual dating and early ultrasound estimates of gestational age, we used a continuous measure of birth weight for gestational age to define four study groups: nongrowth retarded (n = 5163) and mild (n = 411), moderate (n = 226), and severe (n = 147) intrauterine growth retardation. Compared with non-growth-retarded infants of the same gestational age, growth-retarded infants had substantially lower lengths, head circumferences, and proportionality ratios, and the magnitude of the deficits increased significantly with increasing degrees of growth retardation. When the comparison was based on birth weight rather than gestational age, however, growth-retarded infants had slightly but significantly greater lengths and head circumferences, with increased variability in body proportions, but no evidence of the bimodality that would characterize two distinct subtypes. The analysis suggests that proportionality among intrauterine growth-retarded infants represents a continuum, with progressive disproportionality as severity of growth retardation increases. Moreover, despite evidence of some "sparing," the absolute magnitudes of the deficits in length and head growth remain substantial.