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Published on: June 29, 2013
Ponderal index is a poor predictor of in utero growth retardation
P Haggarty1, D M Campbell, A Bendomir
1Rowett Research Institute, Aberdeen, UK.
Insights
Body weight alone is a better indicator of intrauterine growth restriction (IUGR) than ponderal index (PI). This finding helps identify thinness and organ asymmetry in newborns more effectively.
Area of Science:
- Perinatal Medicine
- Neonatalogy
- Pediatric Endocrinology
Background:
- Intrauterine growth restriction (IUGR) is a significant concern in perinatal medicine, affecting fetal development and neonatal outcomes.
- Accurate identification of IUGR and its manifestations, such as asymmetric growth and organ abnormalities, is crucial for timely intervention.
Purpose of the Study:
- To assess the utility of ponderal index (PI) and other weight-length indices in detecting asymmetric growth, body thinness, and organ asymmetry associated with IUGR.
- To compare the predictive power of simple body weight against PI for identifying IUGR-related anthropometric and organometric deviations.
Main Methods:
- A cross-sectional study involving a large cohort of term singleton live births (n=53,934) and stillbirths (n=103) from Aberdeen Maternity Hospital.
- Utilized linear and multiple stepwise linear regression to analyze the association between direct IUGR measures and various weight/length indices.
- Measured birth weight, length, skinfold thicknesses, and by ultrasound, abdominal circumference, biparietal diameter, and femur length; organ-to-brain ratios were assessed in stillbirths.
Main Results:
- Simple body weight was a superior predictor of skinfold thickness, abdominal circumference, and abdominal circumference-to-biparietal diameter ratio compared to PI and other weight-length power indices.
- Gestational age did not significantly improve the predictive ability of body weight for term births.
- Body weight, unlike PI, showed significant differences between stillborn fetuses with acute and chronic anoxic death, which also exhibited distinct organ ratios.
Conclusions:
- Body weight alone is a more effective predictor of anthropometric ratios, organ asymmetry, and thinness associated with IUGR than the ponderal index.
- Incorporating length terms, especially at higher powers, generally diminished the predictive accuracy of these indices.
- The findings suggest that simple body weight measurements are more valuable than PI for identifying IUGR-related fetal growth disturbances.
Objective:
To evaluate the usefulness of ponderal index (PI) and related indices of weight and length in identifying asymmetric growth, body thinness and organ asymmetry associated with IUGR.
Design:
Cross sectional study.
Setting:
Aberdeen Maternity Hospital.
Population:
The population includes term (>/=37 weeks) singleton live births (n= 53,934) between 1986 and 1996, ultrasound measurements in 2522 pregnancies, 712 unselected term pregnancies in 1979/1980 and stillbirths (24-36 weeks) between 1986 and 1995 where the fetus was diagnosed as suffering from acute (n= 73) or chronic (n= 30) anoxic death.
Methods:
The strength of association between direct measures of IUGR and various indices of weight and length was determined by linear and multiple stepwise linear regression.
Main Outcome Measures:
Weight, length, PI and skinfold thicknesses (triceps, biceps, flank thighs, back) were measured at birth. Abdominal circumference, biparietal diameter and femur length were measured by ultrasound at >/=37 weeks. Ratio of liver, heart and kidney to brain were measured in stillbirths.
Results:
Weight alone was a better predictor of skinfold thickness, abdominal circumference and the ratio of abdominal circumference to biparietal diameter than weight divided by length raised to the power 1, 2, 3 (PI), 4 or 5. The inclusion of gestational age made little difference to the predictive ability of weight for these full term births. Weight, but not PI, was significantly different between the two groups of stillborn fetuses (chronic and acute), which had significantly different (P < 0.001) organ ratios.
Conclusion:
Body weight alone was a better predictor of anthropometric ratios, organ asymmetry and measures of thinness at birth thought to be associated with IUGR than the PI. The inclusion of a length term generally reduced the predictive ability with the highest powers resulting in the poorest prediction.

