‘Obesity’ in infancy doesn’t predict obesity in childhood

John Murphy, MDLinx | August 06, 2018

Although overweight infants are likely to remain overweight as children, more than half of very heavy (“obese”) infants have a normal body-mass index (BMI) by age 8, according to the results of a meta-analysis published recently in Pediatric Obesity.

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Chubby babies are likely to become overweight children, but most obese children weren’t unusually heavy as infants, researchers found.

“‘Obesity’ in infancy is not in fact an important risk factor for obesity in childhood,” wrote investigators led by Charlotte M. Wright, MBBS, MSc, MD, professor, Community Child Health, School of Medicine, Dentistry & Nursing, University of Glasgow, Glasgow, Scotland, UK.

On the other hand, most youngsters who had high BMI/obesity in mid-childhood had not been very heavy infants, the researchers found.

For this study, Dr. Wright and colleagues gathered data on nearly 2,500 children from three longitudinal growth studies to investigate whether high weight in infancy predicts obesity in childhood. After adjusting for age and sex, they weighed the infants and categorized them as “overweight” (1 to 2 standard deviations [SD]) or “obese” (2 SD or higher).

They found that infants with a high weight (≥ 2 SD) were five times more likely to have BMI ≥ 2 SD at 8 years of age (P < 0.001). However, a full 64% of infants with raised weight (≥ 1 SD) had a normal BMI at 8 years. Among children with a BMI ≥ 2 SD at 8 years old, half had a BMI ≥ 2 SD for the first time at that age—only 22% of 8-year-olds had had raised weight as infants.

“In this study, raised weight in infancy (SD ≥ 1) was a significant risk factor for later overweight, and once a child had become overweight, this tended to persist, with three quarters of those overweight at 8 years having been overweight earlier,” Dr. Wright and coauthors wrote. “However, we also found that over half the infants who were overweight had normal BMI by 8 years.”

These results suggest that infants who are overweight are likely to remain overweight as children, but infants with more extreme BMIs don’t often become obese children. “Thus, a high weight in infancy has a moderate positive predictive value for becoming overweight in mid-childhood, but not for becoming obese, and its sensitivity is very low,” the authors wrote.

What do these results mean for pediatricians and family medicine physicians in clinical practice?

Dr. Wright and coauthors advised that infants “above the normal range will be at some increased risk of later obesity, but most children with high BMI in childhood will emerge from the much larger group of infants with normal weight. Thus, a watch-and-wait approach seems most sensible in infancy while continuing universal interventions, such as those promoting exclusive breastfeeding, supporting healthy complementary feeding, and encouraging physical activity.”

This research was supported by grants from the UK Medical Research Council.

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