A new, large study suggests that treating women who develop diabetes during pregnancy greatly reduces the chances that their baby will become obese during childhood.
The research found that the higher the mother's blood sugar levels, the greater the child's risk of being obese by age 5 to 7, even if the mother wasn't diagnosed with diabetes.
Untreated high blood sugar nearly doubled the child's risk of becoming overweight or obese, said the study's lead author, Dr. Teresa Hillier of Kaiser Permanente's Center for Health Research in Portland, Ore.
That higher risk disappeared, however, when women with diabetes followed a special diet, exercised or were given insulin. Their children had about the same risk of becoming obese as those whose mothers had normal blood sugar, the researchers found.
"The important message is that the risk of child obesity related to gestational diabetes is potentially reversible," said Hillier, adding that high blood sugar during pregnancy is contributing to the nation's epidemic of childhood obesity.
The research, funded by the American Diabetes Association, is in the September issue of the group's journal, Diabetes Care.
Gestational diabetes begins during pregnancy and usually goes away after childbirth. It affects 3 to 8 percent of pregnant women in the United States. The mother's elevated blood sugar can cause the fetus to grow too large, sometimes requiring delivery by Caesarean section and can bring on other health problems for the mother and baby.
Whether a mother's high blood sugar can lead to childhood obesity has been less clear. It was seen in a study of Pima Indians and in some studies of other populations, the researchers said.
Dr. Boyd Metzger of Northwestern University said the Kaiser research complements a study he presented earlier this summer that suggests lowering the threshold for a diabetes diagnosis. His study found the higher the mother's blood sugar, the greater the risk of complications for the newborn, even at levels below the cutoff for diabetes.
The new study "just provides further evidence that we should be making changes in the diagnosis," said Metzger.
Kaiser patient Janelle Peterson said she worried about getting diabetes when she was pregnant in 2001 with her first son, Erick, because of a family history of diabetes.
"I dreaded it because I knew it was going to happen," said Peterson, who lives outside Portland in the town of Scappoose.
With the help of a nutritionist, Peterson said she struggled to change her diet and keep her blood sugar low. During her second pregnancy with now 3-year-old Christian, she needed to use insulin.
"I had to keep telling myself, I'm doing it for my baby, I'm doing it for a healthy baby and I'm doing it for myself," she said.
Peterson said the effort paid off; today both of her sons are healthy and don't have weight problems.
For their study, Hillier and her colleagues analyzed medical records for 9,439 patients in Oregon, Washington and Hawaii who gave birth between 1995 and 2000 and were all screened for diabetes. Their children were weighed between ages 5 and 7.
Of the children whose mothers had normal blood sugar levels, 24 percent were overweight and 12 percent were obese. For untreated high blood sugar, 35 percent of the children were overweight and 20 percent were obese.
In the treated diabetes group, 28 percent of the children were overweight and 17 percent were obese. The researchers found no statistical difference between the treated and normal level groups after taking into account other contributing factors for childhood obesity — including the mother's age, weight gain during pregnancy, size of the baby and ethnicity.
They calculated that children from the untreated highest levels were 89 percent more likely to be overweight and 82 percent more likely to be obese, compared to children whose mothers had normal levels. Even those children who had normal birth weights were at increased risk of obesity, the researchers said.