How fatness gets forecast in the womb

Children born of mums with gestational diabetes will tend to become fat, say Garvan scientists, and the worse mum’s sugar levels during pregnancy, the fatter they will be.
How fatness gets forecast in the womb
Media Release: 28 January 2011

Children born of mums with gestational diabetes will tend to become fat, say Sydney scientists, and the worse mum’s sugar levels during pregnancy, the fatter they will be.

In Australia, roughly 8-10% of pregnant women develop diabetes in pregnancy. The new finding underlines how important it is for women to try and maintain a healthy weight before and during pregnancy for the sake of generations to come.

Drs Sue Mei Lau and Jenny Gunton, from the Garvan Institute of Medical Research, drew their conclusions from a mouse model of gestational diabetes. Their findings are published in the journal Diabetologia, now online.

“If we don’t apply the brakes on gestational diabetes soon, we’re going to see a spiralling of its side effects in coming decades,” said Dr Gunton.

“Those side effects are escalating levels of obesity and diabetes, as well as more difficult births, caesarian sections and a higher risk of sick babies, because diabetes makes the placenta function less well.”

“In our experiments, we looked at mice with diabetes in pregnancy to see what effects it had on their offspring - foetal programming if you like.”

“We found that offspring from diabetic mothers spontaneously get fat on a normal diet. They even tend to eat a bit less than normal, but their metabolic rate is much lower, so that doesn’t compensate.”

“As the offspring get fatter, their bodies become less able to secrete and use insulin, which shows they are in the first stages of developing diabetes themselves.”

“We found it very interesting that there was a direct correlation between maternal blood sugar levels in pregnancy and various metabolic characteristics of the offspring in adult life,” said Dr Lau.

“Higher maternal blood sugars correlated with greater weight and body fat in the offspring as well as changes in expression of certain brain neuropeptides which control energy balance and body weight.”

“These findings should give us an added impetus to screen for diabetes in pregnancy. The trend in Australia is moving towards universal screening of women in the early third trimester.”

Existing studies show that diet and exercise decrease the risk of gestational diabetes and of later Type 2 diabetes.


Women’s weight during pregnancy
Women who start large only need to gain about 4kg in pregnancy. Those who start thin should aim to gain 8 to 12 kg in pregnancy.

Many women gain 20 to 30 kilos in pregnancy - and it doesn’t matter how thin they are at the start, 30 kg is excessive. And so the more weight gained from start to finish, the more likely women are to get diabetes in pregnancy.  The extra weight includes baby, fluid, placenta, extra cardiovascular volume - probably around 6 or 7 kg for a full term baby.

It’s important that women don’t starve themselves, otherwise they’ll start burning fat cells and that produces ketones – not good for baby. They should be eating a normal balanced diet to maintain normal blood sugars.

Caesarian sections
Caesarian section rates vary from hospital to hospital, but would be unlikely to be much less than 30% for any group of women with gestational diabetes in Australia. The national average is around 20-22% for women without diabetes.

The difference in the rate of sections between the two groups is because babies of mothers with gestational diabetes get fatter before they’re born – and if they get fat enough around the middle, there is a risk of getting stuck in the birth canal.

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