Birth Weight Linked to Obesity
Dec. 10, 2001 -- It's true that heavy kids born to overweight parents will likely become hefty adults. But boys who are lightweights at birth -- then have a rapid growth spurt during childhood -- are also very likely to become beefy adults.
A recent study of more than 10,000 boys and girls born in the British Isles looks at the complex factors related to obesity. Of all the factors analyzed before and after the baby's birth -- until the age of 33 -- body weight of both the mother and baby seemed to carry the most... well, weight ...in whether a baby will become obese later on.
A mother's weight when she gives birth "may be a more important risk factor for obesity in the child than birth weight," writes Tessa J. Parsons, an epidemiologist at the Institute of Child Health in London. Her study is published in this month's British Medical Journal.
Nutrition is at the heart of the matter, writes Catherine Law, an epidemiologist with the MRC Environmental Epidemiology Unit in Southampton, England, in an accompanying editorial.
"This pattern of growth is becoming common in developing countries that are experiencing a nutritional transition to Western lifestyles," Law writes, adding that in these countries, women who come from an impoverished childhood tend to be small themselves, which often leads to them having small babies.
Then, Law continues, as the kids grow up, they eat mostly high-fat and high-sugar junk foods, getting little exercise to burn off all the fat and calories. Boys are more aggressive than girls in getting their share of the family's food. Thus begins the male's lifelong pattern of obesity.
Parsons' study examines patterns of child growth before and after they are born to understand why certain adults become obese. She examined records on 10,683 boys and girls born in England, Scotland, and Wales during one week in 1958, analyzing body mass measurements taken at various ages during their lives: at birth and at ages 7, 11, 16, 23, and 33.
She also looked at data on the parents -- whether either the mother or father was fat when the baby was born, the parents' socioeconomic status, the mothers' age, whether she had smoked during pregnancy, whether she had given birth to other children, and how old she was when her baby was born.
Some results were pretty straightforward: hefty mothers gave birth to hefty babies who became overweight adults. But thin babies were also likely to become fat adults -- especially if they reached most of their adult height by age seven, and if their mothers were thin. This pattern was less clear in baby girls and women.
"These findings are potentially important," writes Parsons, because research shows that thin baby boys are at risk for cardiovascular disease, and that baby girls' height seems to determine their risk for heart disease later on.
Law argues that research dollars should be aimed not at developing drug treatments for adult diabetes, but on developing better ways to change children's eating and exercise habits.