Related Experiment Video
Updated: Jun 4, 2026
Scanning Skeletal Remains for Bone Mineral Density in Forensic Contexts
Published on: January 29, 2018
Predicting weight using postmenstrual age--neonates to adults
Anita L Sumpter1, Nick H G Holford
1Department of Anaesthesiology, University of Auckland School of Medicine, Auckland, New Zealand.
Insights
A new mathematical model describes body weight changes from infancy to adulthood using postmenstrual age (PMA). This model accounts for sex differences and variability, offering a single function for weight prediction across the lifespan.
Area of Science:
- Human growth and development
- Pharmacokinetics and pharmacodynamics
- Biostatistics
Background:
- Postmenstrual age (PMA) is a predictor of physiological functions like glomerular filtration rate and drug clearance.
- Current growth charts rely on postnatal age and do not offer a predictive mathematical function for weight.
- A unified mathematical model for weight across the lifespan is needed.
Purpose of the Study:
- To model the pattern and variability of body weight relative to postmenstrual age (PMA).
- To develop a single mathematical function for weight prediction from prematurity through adulthood.
- To incorporate sex-specific differences and between-subject variability into the weight model.
Main Methods:
- Utilized a pooled database of 7164 body weight observations from 5031 individuals (premature neonates to adults).
- Applied nonlinear mixed-effects modeling to analyze body weight and PMA data.
- Modeled fixed effects (PMA, sex) and random between-subject variability.
Main Results:
- A mathematical model combining three sigmoid hyperbolic and one exponential function accurately described the body weight data.
- Females were observed to have approximately 12% lower body weight.
- Between-subject variability in weight decreased exponentially over time, with a portion remaining a constant fraction of the weight asymptote.
Conclusions:
- A straightforward equation can describe body weight changes in relation to PMA and sex.
- The developed model facilitates simulations of typical weight-age distributions.
- This model can aid in assessing appropriate weight for age in pediatric medical contexts.
Objectives:
To describe the pattern and variability of body weight with postmenstrual age (PMA) using nonlinear mixed effect modeling and to create a single mathematical function that can be used from prematurity to adulthood.
Background:
PMA has been shown to predict functional properties of humans such as glomerular filtration rate and drug clearance. Widely used growth charts use postnatal age to predict weight in an idealized population and are not available as a mathematical function.
Methods:
We modeled 7164 body weight and PMA observations from a pooled database of 5031 premature neonates, infants, children, and adults. All subjects were participants in pharmacokinetic or renal function studies. PMA ranged from 23 weeks to 82 years. A mixed effect model was used to describe fixed (PMA, sex) and random between-subject variability.
Results:
A model based on the sum of three sigmoid hyperbolic and one exponential functions described the data. Females were typically 12% lighter in weight. Part of the between-subject variability in weight decreased exponentially with a half-life of 3.5 PMA years, while the remainder stayed a constant fraction of the weight asymptote for each of the four functions.
Conclusions:
The change of weight with PMA and sex can be described with a simple equation. This is suitable for simulation of typical weight-age distributions and may be useful for evaluation of appropriate weight for age in children requiring medical treatment.
More Related Videos
Related Concept Videos
01:52Regression Toward the Mean
01:17Pharmacokinetics in Pediatric Patients: Drug Distribution