Grim data on health risks for children of overweight mothers further reason to tackle worsening problem.

As a nation we are getting fatter, with data from the Ministry of Health's 2015 New Zealand Health Survey showing that 31 per cent of our adults are obese and a further 35 per cent overweight.

This is up from 27 per cent being obese in 2007 and 29 per cent in 2012. We know that obesity increases the risk of heart disease, stroke and diabetes, but new research from the University of Auckland's Liggins Institute out this week shows that things are likely to keep getting worse.

The study, published in Scientific Reports, looked at 26,561 Swedish mothers and their first-born daughters and found that obese mothers were nearly five times more likely than normal-weight mothers to have a daughter who would become obese as an adult.

In what is being described as an intergenerational obesity cycle, the cause of obesity in the daughters seems to be two-fold.

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Firstly an obese pregnant mother could be providing too much nutrition to their baby during gestation, leading to the child adapting to store more body fat. Secondly, family environmental factors such as diet and physical activity - lifestyle choices that the child is brought up around - are also thought to have an effect on their body weight.

Being obese while pregnant has a known association with several adverse pregnancy outcomes, including a greater risk of miscarriage, pre-eclampsia, gestational diabetes, and the need for a caesarean delivery. There is also evidence that the foetuses of obese mothers are more likely to develop insulin resistance while in the womb, which can lead to the child developing type-2 diabetes later in life.

The importance of a healthy pregnancy weight for the mother doesn't just affect her newborn baby, but continues on throughout the life of the child. Research also out this week published in the American Journal of Epidemiology - along with other research published in the journal Pediatrics - found that mothers who were overweight before or during their pregnancy who also had gestational diabetes were 2.5 times more likely to have daughters with early onset puberty and four times more likely to have children with autism when compared to their peers whose mothers were normal weight with no gestational diabetes.

Continuing on through to later life, an animal study published in FASEB showed results which suggest that women whose mothers were obese during pregnancy will have lower egg reserves for their fertile years in life, which could cause issues with conceiving children of their own.

The mouse study showed low egg reserves in all of the daughters whose mothers ate a high-fat and high-sugar diet, regardless of the daughters' diets, implying that the damage to their daughters' eggs is irreversible and complete before she is even born.

These studies taken together provide overwhelming evidence that a mother being overweight or obese immediately before or during pregnancy can adversely affect the long-term health of her children, including the potential for irreversible conditions such as infertility and autism.

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Current predictions put the cost of being overweight and obese on our healthcare system at 4.5 per cent of total spend, or $8 billion over the next decade. This comprises $6 billion to the tax payer-funded health system, and $2 billion in lost productivity due to absenteeism in work and premature death. These numbers are calculated on 2006 data, and do not correct for the large rise in obesity that we have seen in recent years.

From these recent results, New Zealand needs to think carefully about how it will financially support the health of its population in the long term including finding ways of breaking the worsening intergenerational cycle of obesity.