What a mother eats during pregnancy can put her baby at increased risk of obesity, new research presented at an obesity summit in Montreal suggests.

The Canadian Obesity Network's national summit includes more than 800 delegates who are discussing prevention and treatment from public health, nutrition, genetic, legal and policy perspectives. 


A child touches her pregnant mother's stomach at the last stages of her pregnancy. Pregnant women with high cholesterol or fatty acid levels are more likely to have children who later become obese and develop Type 2 diabetes, researchers say. (Regis Duvignau/Reuters)

For doctors and researchers, the prevention focus is starting to shift — to the womb.

Dr. Jill Hamilton, a pediatric endocrinologist at the Hospital for Sick Children in Toronto, said emerging research shows pregnant women with high cholesterol or fatty acid levels are more likely to have children who later become obese and develop Type 2 diabetes.

"Some of these molecules can be transmitted to the baby and influence how the baby develops," Hamilton said. "It may impact on programming pathways in the brain related to appetite."

Factors in the womb can interact to permanently change the expression of genes without actually changing the structure of DNA. The process is known as epigenetics, and the changes can affect how DNA instructions are interpreted as cells, proteins and other building blocks in the body are formed. 

In the obesity research, the "epigenetic" changes relate to appetite regulation. These might affect how the body processes the glucose fuel in food, which increases the likelihood that a child could develop insulin resistance or obesity, Hamilton said.

This week, Dr. Keith Godfrey, a professor of epidemiology and human development at the University of Southhamptom, England, and his colleagues published their findings in the journal Diabetes. For the first time, the study showed a women's nutrition in pregnancy can change how her child's DNA functions and lead the child to put on more fat.

Godfrey's team measured epigenetic markers in nearly 300 children at birth. The markers explained at least 25 per cent of the difference in fatness when the children were studied again at six or nine years of age — or on average a difference of about two kilograms for a 30-kilogram nine-year-old.

"Remarkably, simple changes in mother's nutrition in pregnancy can permanently alter the appetite and the physical activity levels of the offspring," Godrey said of earlier studies on animals.

For Jolyn Swain in Halifax, who is four months pregnant, the research changes everything for her.

"It makes me want to be more involved, it makes me want to keep those food journals and check the boxes," Swain said.

The researchers said they can't prescribe specific foods to eat or avoid during pregnancy. The findings also don't  change current nutritional advice for pregnant women, aside from giving another important reason to follow it.

The conference runs until May 1.

With files from CBC's Pauline Dakin