Pam Levin's daughter weighed less than 5 pounds at birth. But by the time the child turned 3, Levin and her husband had begun to bristle at some of the comments about her. "People would say, ‘She's chunky' or ‘She's a big girl,'" Levin says.
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% 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.'"
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 — the most scientifically rigorous kind that prove 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.
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.
Further, 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% 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, memorialized on the first page of the baby book and never forgotten by his or her mother.
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. A 2008 study in the Archives of Pediatrics & Adolescent Medicine found that babies in child-care centers or cared for by relatives tended to have lower rates of being breast-fed and had solid foods introduced earlier, both factors tied to weight gain.
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.
That's why, Stettler says, "these associations are not ready for prime time or to be converted into public health recommendations."
Other experts say the soaring rates of child obesity warrant changes even without solid evidence.
In a study published recently in Pediatrics, Skinner's team found that obese children as young as age 3 had higher levels of C-reactive protein, a marker for inflammation that is linked to heart disease in adults. C-reactive protein levels can rise for a number of reasons, and about 15% to 20% of children have above-normal levels. But among obese 3-year-olds, 45% had elevated levels. It's not clear yet whether this inflammation remains high in obese children or causes any long-lasting harm.
"That indicates to me that when we see what appears to be a chubby kid on the outside, there may be something different on the inside, compared with healthy kids," she says. "It's a red flag that something is not quite right."
Levin didn't wait for someone to test her daughter's C-reactive protein.
The first-time mom recently consulted a doctor who specializes in weight and nutrition issues, and she learned that the family needed to make immediate changes. A toddler doesn't need a whole bagel with cream cheese and salmon for lunch, she learned. One-quarter of that bagel sandwich would suffice. Low-fat milk is more healthful than whole milk. Snacks need not include juice.
That doesn't mean she put her child on a diet; most doctors discourage such restrictions. "It's not about losing weight," says Levin. "It's about her growing into her weight. We're not focused on numbers and the scale and all of that. We just need to focus on healthy choices."
More parents of young children are asking for advice on weight and nutrition, says Dr. Elaine L. Rosen, director of the California Center for Healthy Living in Encino, where Levin took her daughter. A pediatrician, Rosen opened her center, which addresses weight or nutritional problems in babies through young adults, because of high rates of child obesity and because worried parents didn't know how to help their kids.
Too much concern on the part of parents can backfire, Rosen says, leading to eating disorders in children or contributing to children being overweight or underweight.
"There is a lot of misinformation out there," she says. "A lot of adults rely on diet-mentality notions, which is not appropriate for kids."
Families are taught what, when and where to feed their children, while leaving the questions of whether to eat and how much to eat to the child, Rosen says.
"Sometimes parents cross the line into the domain of control," she says. "The child does not learn to trust themselves to feed themselves properly. Some kids resort to under-eating and picky eating. Some overeat, learn to sneak food and defy their parents."
The emphasis on the early years just makes good sense, Taveras says. "Almost all of the risk factors we found we can change. We can counsel families about these issues."
Levin and her daughter began to see Rosen a few months ago. But already, Levin says, her daughter's preschool teacher has remarked that the child seems to have had a growth spurt — in height.
A late start
So far, the early years have been ignored when it comes to obesity practices and policies. First Lady Michelle Obama recently launched a campaign to address child obesity. But like many other programs, it focuses on school-age children. There is no organized public-health effort on obesity prevention from gestation to age 5. The Institute of Medicine, however, recently convened a task force to study that time period.
Because child obesity is linked to both maternal and child health, obstetricians and pediatricians must be enlisted to address obesity prevention in their patients, Taveras says.
But, she adds, "during pregnancy and the first two years of life, mothers and their infants are seen by physicians more often than any other time of life. It's kind of a golden opportunity. We have systems in place to reach mothers and children."
Obesity Risks Start Before Birth
Prenatal, infancy, early childhood — factors in all may affect a person’s future weight and health.
(Alexandra Grablewski / StockFood / Getty Images)