In the largest study of its kind, US researchers have found that the risk of a child being obese goes up in line with increase in the mother’s sugar levels during pregnancy. Scientists are hopeful that treating more women for diabetes during pregnancy could help to reduce the incidence of childhood obesity.

The study is published in the September issue of the journal Diabetes Care and is available as an early online edition. It is the work of researchers at the Kaiser Permanente Center for Health Research (CHR) in Portland, Oregon, and Hawaii.

The study shows that the risk of childhood obesity goes up in line with the amount of blood sugar in pregnant women, and suggests that untreated diabetes in a pregnant woman nearly doubles the risk of the child she is carrying being obese by the time he or she reaches between 5 and 7 years of age.

The researchers also found that when pregnant women were treated for diabetes, the risk of childhood obesity went down to the same level as children whose mothers had normal blood sugar levels in pregnancy.

Lead author Dr Teresa Hillier, an endocrinologist and senior investigator at CHR Northwest and Hawaii, said:

“Hyperglycemia [high blood sugar] during pregnancy is clearly playing a role in America’s epidemic of childhood obesity.”

“The key finding here is that the risk of overweight and obese children rises in step with higher levels of blood sugar during pregnancy. The good news for pregnant women is that by treating gestational diabetes, your children’s risk of becoming overweight or obese drops considerably,” added Hillier.

Around 8 per cent of pregnant women a year in the US have gestational diabetes, where the mother’s blood glucose level is raised (hyperglycemia) and insulin resistance develops due to the pregnancy.

Childhood obesity has been rising at an alarming rate among Americans: it has more than doubled in the last 20 years. Estimates suggest that 7 million children in the US today who are either overweight or obese will grow into overweight or obese adults, a real time bomb of a health problem for the nation.

Hillier and colleagues used CHR’s records to analyse data on 9,439 mother-child pairs who were members of the organization’s health plan in Oregon, Washington and Hawaii. The children were born between 1995 and 2000.

Hillier’s advice to pregnant women is they should talk to their doctor about diabetes screening, and if they need it then they should work with their doctor and stick to the treatment.

“It’s the best thing you can do to reduce your child’s risk of obesity,” she said.

The pregnant women in the study had their blood sugar level assessed and were screened for gestational diabetes. Once born the children were followed and weighed between the ages of 5 and 7. This is the age when body fat reduces to a minimum and then increases again into adulthood. It is known as the “adiposity rebound” period and is a strong predictor of adult obesity.

The relationship between the mothers’ blood sugar levels during pregnancy and childhood obesity was then analysed.

The results showed that children born to mothers who had high blood sugar and were not treated for it had an 89 per cent higher risk of being overweight and 82 per cent higher risk of being obese by the time they were aged between 5 and 7 years. This was compared to children whose mothers’ blood sugar was normal when they carried them in the womb.

The risk of being overweight or obese of children born to mothers who were treated for gestational diabetes when pregnant was statistically no different to that of children born to mothers who had normal blood sugar levels when pregnant.

Hillier said this suggested the “metabolic imprint” for childhood obesity linked to gestational diabetes may be reversible.

“Childhood Obesity and Metabolic Imprinting: The ongoing effects of maternal hyperglycemia.”
Teresa A. Hillier, Kathryn L. Pedula, Mark M. Schmidt, Judith A. Mullen, Marie-Aline Charles, and David J. Pettitt
Diabetes Care 30: 2287-2292
DOI: 10.2337/dc06-2361

Click here for Abstract.

Written by: Catharine Paddock