Treating women who develop diabetes during pregnancy greatly reduces the chances that their baby will become obese during childhood, reports a study in Diabetes Care.
Untreated high blood sugar nearly doubled the child's risk of becoming overweight or obese by age five to seven, found the study, led by Dr. Teresa Hillier of Kaiser Permanente's Center for Health Research in Portland, Ore.
The higher the mother's blood sugar levels, the greater the child's risk.
That risk disappeared, however, when women with diabetes followed a special diet, exercised or were given insulin. In fact, their children had about the same risk of becoming obese as those whose mothers had normal blood sugar.
Gestational diabetes begins during pregnancy and usually goes away after childbirth. The mother's elevated blood sugar can cause the fetus to grow too large, sometimes requiring delivery by Caesarean section.
Approximately 3.5 per cent of non-Aboriginal women in Canada develop gestational diabetes, and up to 18 per cent of Aboriginal women will develop it.
Whether a mother's high blood sugar can lead to childhood obesity has never been clear.
For their study -- the largest of its kind -- Hillier and colleagues looked at the medical records for 9,439 U.S. mothers who gave birth between 1995 and 2000 and were screened for diabetes. Their children were then weighed between ages 5 and 7.
Of the children whose mothers had normal blood sugar levels, 24 per cent were overweight and 12 per cent were obese. For those whose mothers had untreated high blood sugar, 35 per cent of the children were overweight and 20 per cent were obese.
In those whose mothers had their diabetes treated, 28 per cent of the children were overweight and 17 per cent were obese.
They calculated that children from the untreated highest levels were 89 per cent more likely to be overweight and 82 per cent 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.
"The key finding here is that the risk of overweight and obese children rises in step with higher levels of blood sugar during pregnancy," said Hillier, adding that the problem is contributing to the nation's epidemic of childhood obesity.
"The good news for pregnant women is that by treating gestational diabetes, your children's risk of becoming overweight or obese drops considerably."
"My advice to pregnant women is three-fold: Discuss gestational diabetes screening with your doctor, usually between weeks 24 and 28 of pregnancy; if you have gestational diabetes, work with your physician to treat it, and stick with the treatment during your pregnancy. It's the best thing you can do to reduce your child's risk of obesity," said Hillier.
