The comments may not have been tactful, but the Los Angeles mom caught herself wondering if they were true. Was the adorable, easygoing preschooler overweight? During the child's first year of life, she had been smaller than 95 percent of children her age, according to pediatric growth charts, weighing about 17 pounds on her first birthday. but her weight had increased, and kept increasing, until she was 43 pounds at age 3 1/2.
"All of a sudden she's was on the 50th percentile, then the 75th, then 99th," Levin recalls. "You say, 'Wait a minute. Something's not right.' "
Risk FactorsBefore Birth
Today, one of every three U.S. children is overweight - but it's much easier to prevent obesity than to treat it. That's why pediatric obesity experts now say intervention should begin early - very early. the risk of becoming overweight or obese, it increasingly seems, begins before a child is born, establishes roots in infancy and may be entrenched by the time a tot starts kindergarten.
In recent studies, researchers concluded that some risk factors for childhood obesity exist even before birth. Further, they've found, obese 3-year-olds already show the signs of inflammation that is linked to heart disease in adults.
The notion that a person's lifelong weight trajectory might be programmed early in life is startling - and potentially revolutionary, says Dr. Nicolas Stettler, an associate professor of pediatrics and epidemiology at the University of Pennsylvania.
"If we can identify a short period of time where an intervention can have a long-lasting effect, that could be very promising," he says.
So far, most of the evidence that the early years affect weight into adulthood comes from observational or epidemiological studies. There are few randomized, controlled trials to indicate cause and effect, says Dr. Elsie M. Taveras, an assistant professor of population medicine and pediatrics at Harvard Medical School. but she points out, "We have pretty strong observational studies for a good number of risk factors in the prenatal, infancy and early childhood period."
In her paper, published March 1 in the journal Pediatrics, Taveras and her colleagues summarized more than one dozen factors in the prenatal period through age 5 that can increase the likelihood of later obesity. the research was based on a study of 1,826 mother-child pairs from pregnancy through the child's first five years of life.
Many were behaviors that are often passed down through generations and are more likely to be found in black and Latino families than in white families, possibly accounting for the high rates of obesity in those communities. For example, black and Latino infants are more likely to be fed solid food before 4 months of age and to sleep less as infants.
Each of the three early-life stages - prenatal, infancy and early childhood - comes with its own risk factors. but each also comes with the chance to intervene, breaking a lifetime cycle of obesity and dieting before it starts.
Several risk factors likely begin with the mother - even before she's a mother.
Overweight Mothers
Almost half of U.S. women today begin pregnancy overweight or obese, automatically increasing the likelihood that their babies will be born either too small or too large, both of which increase the risk of obesity for the child later in life.
Studies show that how much weight a pregnant woman gains and whether she develops gestational diabetes both can influence her child's weight in adulthood.
The odds of being overweight at age 7 were 48 percent higher for children of women who gained more weight than recommended during pregnancy compared with women who met weight guidelines, according to a study by Stettler and colleagues published in 2008 in the American Journal of Clinical Nutrition.
"What we find is that these things set up children for a lifelong risk of obesity," says Asheley Cockrell Skinner, an assistant professor of pediatrics at the University of North Carolina School of Medicine. "These factors don't just make them overweight; they become barriers to helping them change when they get older. it becomes the story that never ends."
A newborn's weight is noted on birth announcements and never forgotten by his or her mother.
First-yearWeight Gain
But perhaps it's a baby's weight at age 1 that matters more, experts say. Weight that is too high for the child's height - for example, being at the 75th percentile for weight but the 30th percentile for height - can spell trouble.
Another study from Taveras' research group, published last year in Pediatrics, found that rapid increases in weight-for-length measurements during the first six months of life were associated with a greatly increased risk of obesity at age 3.
No one is sure why rapid weight gain in the first year is important. it could be that when a baby is fed more than it needs, the brain's development is affected so that it signals the need for excessive amounts of food, Stettler says.
Likewise, too much food might program an infant's pancreas, and the body's response to insulin, in a manner that leads to obesity.
Whatever the cause, Taveras says, "excessive weight gain in those first six months of life is not baby fat that is going to go away. We're going to have to change perceptions about what's healthy and what's not healthy."
Whether a baby is breast-fed (and for how long) or bottle-fed, when it begins eating solid food and how much it sleeps have also been linked to obesity risk.
But studies on breast-feeding are an example of a weakness in the argument that the early years influence future weight, Stettler says.
For example, one study randomly assigned the mothers of infants to a program that encouraged breast-feeding and compared them with women who did not receive the breast-feeding promotion program.
More babies were indeed breast-fed in the first group. but when the children in both groups reached age 6, there were no differences in their weight. the paper was published in 2007 in the American Journal of Clinical Nutrition.
"We know that families that choose to breast-feed are very different from families that do not," Stettler said.
They may have higher incomes or feed their children more healthful food. Thus, it's hard to say whether breast-feeding or other family characteristics affect a child's future risk of obesity.