Prevalence of overweight and obese children between 1989 and 1998: population based series of cross sectional studies

Abstract

Objective: To determine trends in weight, height, and body mass index in children between 1989 and 1998.

Design: Retrospective series of cross sectional studies of routinely collected data.

Setting: Primary care in the Wirral Health Authority.

Participants: 35 662 infants aged 1-3 months (representing 88% of live births) and 28 768 children aged 2.9-4.0 years. 21 582 infants and children (25.1%) were excluded because of missing or inaccurate data.

Main outcome measures: Weight, height, sex, and age routinely recorded by health visitors. Height, weight, and body mass index standardised for age and sex. SD score >1.04 for body mass index (>85th centile) was defined as overweight and >1.64 (>95th centile) as obese. Body mass index was not calculated in infants as it is difficult to interpret.

Results: From 1989 to 1998 there was a highly significant increasing trend in the proportion of overweight children (14.7% to 23.6%; P<0.001) and obese children (5.4% to 9.2%; P<0.001). There was also a highly significant increasing trend in the mean SD score for weight (0.05 to 0.29; P<0.001) and body mass index (-0.15 to 0.31; P<0.001) but not height. Infants showed a small but significantly increasing trend in mean SD score for weight (-0.17 to -0.05; P=0.005).

Conclusions: From 1989 to 1998 there was a highly significant increase in weight and body mass index in children under 4 years of age. Routinely collected data are valuable in identifying anthropometric trends in populations.

Figure 1

Mean SD scores for weight, height, and body mass index plotted against year of measurement for children aged 2.9 to 4 years. Increasing trend in scores significant for weight and body mass index but not for height (Pearson's correlation (95% CI) and P for r=0 (weighted): 0.94 (0.77 to 0.99), P<0.001; 0.93 (0.71 to 0.98), P<0.001; and 0.61 (−0.03 to 0.90), P=0.059)

Figure 2

Annual increase in proportion of overweight and obese children; χ² for trend in overweight 71.1 (P<0.001) for boys and 33.1 (P<0.001) for girls, for trend in obesity 48.3 (P<0.001) for boys and 7.3 (P=0.007) for girls. Proportion of overweight and obese boys becomes greater than girls in early 1990s and remains so

Figure 3

Median SD scores for weight at 6 weeks bounded by interquartile range plotted against year of measurement for infants aged 1 to 3 months (Pearson's correlation (95% CI) 0.80 (0.35 to 0.95), P=0.005 for r=0)