Infant weight gain may be clue to adult obesity

Infants who gain weight quickly in the first few months after birth may be more likely to be obese as young adults, suggests new evidence.

A study on African Americans found that those who gained weight rapidly in the first four months of life were more likely than their peers to be obese 20 years later.

The researchers from The Children's Hospital of Philadelphia and the University of Pennsylvania in the US analysed data on 300 people in Philadelphia who were followed as part of a long-term, larger study from 1962 to 1989. Obesity is reaching epidemic proportions among both children and adults in the US, and obesity rates are particularly high among African Americans.

"This study establishes, for the first time to our knowledge, that a rapid infant weight gain pattern from birth to age four months is associated with obesity in young adulthood,"​ said Dr Nicolas Stettler, a pediatric nutrition specialist at The Children's Hospital of Philadelphia and primary investigator of the study.

"This suggests that early infancy constitutes a critical period for the development of adulthood obesity,"​ added Dr Stettler.

Around 29 per cent of the subjects had a rapid early infancy weight gain, and the prevalence of adult obesity was 8 per cent. Subjects with a rapid early infant weight gain were more than twice as likely to be obese 20 years later than subjects without rapid early infant weight gain, reported the researchers. (The risk for adult obesity increased with more rapid rates of weight gain in early infancy.)

Rapid infancy weight gain is when weight gain exceeds average patterns of growth during infancy. In this study, those who gained more than 8 to 10 pounds between birth and age four months had a 14 per cent risk of becoming obese at age 20 years, compared to 6 per cent of those who gained less. The average weight gain in the first four months of life was about 7 to 8 pounds.

"This may lead to new hypotheses to origins of obesity and to new approaches for obesity prevention,"​ said Dr Stettler. While further research is needed, he added that the American Association of Pediatrics recommends exclusive breastfeeding during the first six months of life, a practice generally associated with a slower rate of weight gain and possibly a decreased risk for overweight in childhood and adolescence. Unfortunately the database from which this study was drawn did not include information on breastfeeding.

The new results, published in the June issue of the American Journal of Clinical Nutrition​, back previous research by Stettler that found that rapid weight gain during the first four months of life was significantly associated with an increased risk of being overweight at age seven, regardless of birth weight and weight at one year of age. That study reflected a much larger sample of both white and African American children from 12 US cities, of which the current population is a subset. Data were drawn from The National Collaborative Perinatal Project.

Researchers also added that the prevalence of obesity found in the study for African American young adults and their mothers was considerably lower than the prevalence observed today in African American adults and women of childbearing age. Therefore the public health impact of the findings may be more important today than for the period when these data were collected, added Stettler.