【单选题】

Schools have banned cupcakes, issued obesity report cards and cleared space in cafeterias for salad bars. Just last month, Michelle Obama’s campaign to end childhood obesity promised to get young people moving more and improve school lunch, and beverage makers said they had cut the sheer number of liquid calories shipped to schools by almost 90 percent in the past five years.

But new research suggests that interventions aimed at school-aged children may be, if not too little, too late. More and more evidence points to crucial events very early in life—during the toddler years, infancy and even before birth—that can set young children on an obesity track that is hard to alter by the time they’re in kindergarten. The evidence is not invulnerable, but it suggests that prevention efforts should start very early.
Among the findings are these: The chubby angelic baby who is growing so nicely may be growing too much for his or her own good, research suggests.Babies whose mothers smoked during pregnancy are at risk of becoming obese, even though the babies are usually small at birthBabies who sleep less than 12 hours are at increased risk for obesity later. If they don’t sleep enough and also watch two hours or more of TV a day, they are at even greater risk.
Some early interventions are already widely practiceD、Doctors recommend that overweight women lose weight before pregnancy rather than after, to cut the risk of obesity and diabetes in their children; breast-feeding is also recommended to lower the obesity risk.But weight or diet restrictions on young children have been avoideD、" It used to be kind of taboo to label a child under 5 as overweight or obese, even if the child was—the thinking was that it was too disgraceful, " saidDr.Elsie M. Taveras of Harvard Medical School, lead author of a recent paper on racial difference in early risk factors.
Scientists worry about what are called epigenetic changes. The genes inherited from mother and father may be turned on and off and the strength of their effects changed by environmental conditions in early development. Many doctors are concerned about women being obese and unhealthy before pregnancy because, as they point out, the womb is the baby’s first environment.Experts say change may require abandoning some cherished cultural attitudes. " The idea that a big baby is a healthy baby, and a crying baby is probably a hungry baby who should be fed, are things we really need to rethink, "Dr.Birch saiD、
Evidence shows that the earliest trend of obesity may start______.A．from kindergarten age
B．as early as infancy period
C．before birth
D．as early as school age