We all know that smoking and drinking when pregnant can harm the baby, but new research published in The Journal of Physiology suggests that poor diet may also cause long-lasting, irreversible damage in offspring from heart disease to diabetes.
Stéphanie Bayol and Neil Stickland at the Royal Veterinary College, London fed female rats a "junk food" diet of crisps, cheese, muffins and other processed foods throughout pregnancy and lactation.
The offspring, who were overweight at birth, were born with a taste for junk-food themselves. But even when fed a healthy diet, the junk-food babies had a host of medical problems that lasted beyond adolescence into adulthood.
The rats had raised cholesterol and triglyceride levels - both associated with heart disease. Insulin and glucose in the blood were also unusually high, known to be a cause of type-2 diabetes. And the rats remained significantly podgier than normal with extra fat around the kidneys, another diabetes risk-factor.
The female offspring were particularly badly affected, expressing high levels of glucose and the appetite-promoting hormone leptin making them very prone to obesity.
"It seems that a mother's diet whilst pregnant and breastfeeding is very important for the long term health of her child," says Dr Bayol. "This does not mean that obesity and poor health is inevitable and it is important that we take care of ourselves and live a healthy lifestyle. But it does mean that mothers must eat responsibly whilst pregnant."
But will these results translate to humans? Very probably, says Professor Stickland. "Humans share a number of fundamental biological systems with rats, so there is good reason to assume the effects we see in rats may be repeated in humans," he says. "Our research certainly tallies with epidemiological studies linking children's weight to that of their parents."