Babies born to obese mothers may face an increased risk of dying early from heart problems in their adult life, according to research published late Tuesday that paints an alarming picture of the future as obesity-related disease is handed down from one generation to the next.

The comprehensive study looked at nearly 30,000 women who gave birth in Aberdeen between 1950 and 1976 and who were weighed and measured in early pregnancy. When the researchers then searched for death certificates among the nearly 38,000 children – by then aged 34 to 61 – they found that those whose mothers had been obese had a 35% higher chance of dying as a result of cardiovascular disease than the children of normal-weight mothers. Health records showed that they also had a 42% higher risk of being treated in hospital for heart problems.

Experts called for more effort to educate young women who might become pregnant about good eating habits and exercise as the implications of the study became clear. One in five pregnant women today is obese. If the researchers are right, the UK could face a huge rise in heart disease and early deaths as the children of these obese mothers hit middle age.

Obesity often runs in families and the researchers accept it is hard to separate the effects of growing up in a household where overweight is the norm, an excess of fattening food is available and no one is playing sport.

But, they say, it is well known that premature, undernourished, severely underweight babies run a higher risk of heart problems and cancer. They theorise that babies may also suffer long-term health problems if they receive too much nutrition in the womb. Animal studies show that developmental over-nutrition can cause permanent changes in appetite control and energy metabolism.

At the time that the mothers in the study gave birth, only 21% were overweight and 4% were obese. Now 20% are obese.

"With the rising rates of excess weight among pregnant women, our findings of an association between maternal overweight and obesity and premature death in the adult offspring is a major public health concern," write the authors, Rebecca Reynolds, professor of metabolic medicine at Edinburgh University and colleagues in the British Medical Journal.

Reynolds stressed that their findings should not be used to blame women.

"We don't want to be blaming anybody at all, just highlighting that we have found an association," she told the Guardian. "Ideally we'd like to understand more about the mechanisms. We want to see whether it is possible to help women planning a pregnancy to be a healthy weight." She would like greater public awareness that starting pregnancy at a healthy weight was best both for mother and child, she added.

In a BMJ editorial on the study , Dr Pam Factor-Litvak from the department of epidemiology at Columbia University in New York says that the paper leaves open two questions – the effect of the child's environment while growing up and the influence of a father's obesity.

At the moment, she adds, US guidelines recommend that overweight women should not put on more than 5kg-9kg (11lb-20lbs) during pregnancy, which is less than the 7kg-11kg recommended for normal-weight women, but if the study is correct, there needs to be action to help women before they get pregnant.

Dr Tim Chico, consultant cardiologist at Sheffield Teaching Hospitals, said it was a worrying finding.

"It suggests the current obesity epidemic will lead to an increased risk of heart disease even in babies born in the future," he said. It was unclear whether pregnancy, genes or the environment in early childhood were the issue, but either way, the study emphasised the importance of trying to maintain a healthy weight.

"No parent wants to think that their actions might affect the health of their children, and this is often a powerful motivation to change our behaviour. The message of this study is clear; if a mother is overweight, it may be her children that pay the price.

"The causes of obesity are complex, and it is not just the fault of the person who is overweight. We have made ourselves a society where it is difficult to take exercise, due to pressure of time and lack of opportunity, but very easy to find cheap, high-calorie food. I've seen heart disease decline over my career, but it is quite possible this will reverse as we begin to see the consequences of an environment that makes it very difficult to stay thin."

Doireann Maddock, senior cardiac nurse at the British Heart Foundation (BHF), which part-funded the study, said that while more research was needed to understand the association between the pregnant mother's weight and her child's chances of dying prematurely in adulthood, the study "emphasises the need for everyone, but in particular pregnant women, to try to eat healthily and be active".

Dr Susan Ozanne, reader in developmental endocrinology at the University of Cambridge and British Heart Foundation senior fellow, said: "Although these findings are interesting and important, until the confounding effects of other factors such as obesity in the offspring themselves can be accounted for, we cannot assume a causal relationship between obesity in pregnancy and heart problems in adult children of these women – more research is needed to establish this."

She and other experts warned that pregnant women should not embark on a diet that could possibly do more harm to their unborn child.

"It is a complex issue which definitely needs more research. Until we have the results of further research, it would be unwise for any pregnant woman to drastically change their diet as this may be harmful in both the short and long term to both mother and child," she said.