Risk factors for obesity in 7-year-old European children: the Auckland Birthweight Collaborative Study

Blair, Nikki J
Thompson, John M D
Black, Peter N
Becroft, David M O
Clark, Phillipa M
Han, Dug Yeo
Robinson, Elizabeth
Waldie, Karen E
Wild, Chris J
Mitchell, Edwin A

¹Department of Paediatrics, University of Auckland, Auckland, New Zealand
²Department of Pharmacology and Clinical Pharmacology, University of Auckland, Auckland, New Zealand
³Department of Obstetrics and Gynaecology, University of Auckland, Auckland, New Zealand
⁴Department of Epidemiology and Biostatistics, University of Auckland, Auckland, New Zealand
⁵Department of Psychology, University of Auckland, Auckland, New Zealand
⁶Department of Statistics, University of Auckland, Auckland, New Zealand

Correspondence to: Professor Ed Mitchell Department of Paediatrics, University of Auckland, Private Bag 92019, Auckland, New Zealand;[email protected]

Accepted 25 July 2007

We sincerely thank the parents and children for participating in these studies.

The initial study was funded by the Health Research Council of New Zealand. The 12-month postal questionnaire was funded by Hawkes Bay Medical Research Foundation. The 3.5-year follow-up study was funded by the Child Health Research Foundation, Becroft Foundation and Auckland Medical Research Foundation. The 7-year follow-up study was funded by the Child Health Research Foundation. The 3.5- and 7-year follow-up studies were conducted in the Children’s Research Centre which is supported in part by the Starship Foundation and Auckland District Health Board. EA Mitchell and JMD Thompson are supported by the Child Health Research Foundation.

Competing interests: None.

Archives of Disease in Childhood 92(10):p 866-871, October 2007.

Objective:

To identify risk factors associated with obesity in primary school children, with a particular focus on those which can be modified. To identify critical periods and growth patterns in the development of childhood obesity.

Methods:

871 New Zealand European children were enrolled in a longitudinal study at birth and data were collected at birth, 1, 3.5 and 7 years of age. Data collected at 7 years included weight, height, bioelectrical impedance analysis (BIA), television viewing time and a 24 h body movement record (actigraphy). The outcome measure was percentage body fat (PBF), which was calculated at 3.5 and 7 years using BIA. Univariate and multiple regression analyses were carried out using PBF as a continuous variable.

Results:

Multivariable analysis found maternal overweight/obesity, maternal age, female gender, sedentary activity time and hours of television viewing to be independently associated with PBF at 7 years. Growth variables (birth weight, rapid weight gain in infancy, early (1–3.5 years) and middle childhood (3.5–7 years)) were also independently associated with adiposity at 7 years. There was a strong correlation between PBF at 3.5 years and PBF at 7 years.

Conclusions:

Many primary school aged children start on the trajectory of obesity in the preschool years, which suggests interventions need to start early. Maternal overweight/obesity, television watching, sedentary activity time and rapid weight gain in infancy, early and middle childhood are risk factors for childhood obesity, and are all potentially modifiable.