A Novel Method to Describe Early Offspring Body Mass Index (BMI) Trajectories and to Study Its Determinants.
BACKGROUND
Accurately characterizing children's body mass index (BMI) trajectories and studying their determinants is a statistical challenge. There is a need to identify early public health measures for obesity prevention. We describe a method that allows studies of the determinants of height, weight and BMI growth up to five years of age. We illustrated this method using maternal smoking during pregnancy as one of the early-life factors that is potentially involved in prenatal programming of obesity.


METHODS
Individual height and weight trajectories were fitted using the Jenss-Bayley model on 28,381 and 30,515 measurements, respectively, from 1,666 children to deduce BMI trajectories. We assessed global associations between smoking and growth trajectories and cross-sectional associations at specific ages.


RESULTS
Children exposed in late pregnancy had a 0.24 kg/m2 (95% confidence interval: 0.07, 0.41) higher BMI at 5 years of age compared with non-exposed children. Although the BMIs of children exposed during late pregnancy became significantly higher compared with those of non-exposed children from 2 years onwards, the trajectories began to diverge during the first weeks of life.


CONCLUSIONS
Our method is relevant for studies on the relationships between individual-level exposures and the dynamics and shapes of BMI growth during childhood, including key features such as instantaneous growth velocities and the age or BMI value at the BMI infancy peak that benefit from the monotonic pattern of height and weight growth.
Early determinants of the child's health and development Team (ORCHAD), INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Paris, F-75014 France.|Paris Descartes University, Paris, France.|Univ Paris-Sud, Villejuif, France.
Sophie
S
Carles
Early determinants of the child's health and development Team (ORCHAD), INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Paris, F-75014 France.|Paris Descartes University, Paris, France.
Marie-Aline
MA
Charles
Early determinants of the child's health and development Team (ORCHAD), INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Paris, F-75014 France.|Paris Descartes University, Paris, France.
Anne
A
Forhan
Team of Environmental Epidemiology applied to Reproduction and Respiratory Health, Inserm, CNRS and University Grenoble Alpes joint research center, Institute of Advanced Biosciences, U1209, Grenoble, France.|Grenoble Alpes University, Institute of Advanced Biosciences, U1209, Grenoble, France.
Rémy
R
Slama
Early determinants of the child's health and development Team (ORCHAD), INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Paris, F-75014 France.|Paris Descartes University, Paris, France.
Barbara
B
Heude
Early determinants of the child's health and development Team (ORCHAD), INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Paris, F-75014 France.|Univ Paris-Sud, Villejuif, France.|Laboratoire de biomathématique, Faculté de Pharmacie, Univ Paris-Sud, Châtenay-Malabry, F-92290, France.
Jérémie
J
Botton
D000328:Adult; D000886:Anthropometry / Q000379:methods*; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D048788:Growth and Development; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009035:Mothers; D011247:Pregnancy; D012907:Smoking