The country's most influential scientist is calling for all pregnant women to be tested for diabetes to break the obesity cycle.

A mother's diet can determine a child's future weight, and risk of diabetes and heart disease, according to research by Sir Peter Gluckman, chief science adviser to the prime minister.

In a dangerous cycle, the new generation of children are then more likely to pass bad eating habits and diabetes to their children.

"The rising rates of gestational diabetes and maternal obesity are a real concern. All New Zealand women should have a glucose tolerance test during pregnancy," Gluckman wrote in his submission to a health select committee on September 26. He said the current burden of gestational diabetes is probably being "grossly underestimated".

AUT nutrition professor Elaine Rush said three in 100 women now develop gestational diabetes, but in the next 10 years it will be one in four.

She said testing every mother for gestational diabetes will work only if there are support services to back it up.

Many women do not realise their children's future health stems from what they eat when pregnant, she said.

If a mother has gestational diabetes her child is four times more likely to have diabetes within their lifetime.

Diet and exercise can help reduce the risk of gestational diabetes, and thus lessen the risk on the unborn child.

- © Fairfax NZ News