Women need to be healthier before they conceive or risk their child developing a host of health problems, experts have warned.
Babies are being put at risk of brain damage, stroke, heart attack or asthma in adulthood because their mother was obese, scientists say.
A series of studies suggest the problem begins in the womb - with the time before couples begin a family representing a 'missed opportunity' to tackle it.
Research has also shown youngsters are more likely to pile on the pounds if their parents were overweight before they were born.
Leading doctors argue a new approach is needed to motivate future parents to live a healthier lifestyle.
Mothers-to-be should be leading healthier lifestyles before they conceive to reduce the amount of childhood obesity, a study has found
There is now a wealth of evidence the risk of obesity and its associated conditions, such as heart disease diabetes and some cancers, could impact the developing baby.
In turn, when the child becomes a young adult they may pass the risk of obesity on to their children.
Many young people, whilst appearing outwardly healthy, are nonetheless on a risky path to obesity and chronic disease and more likely to pass this risk to their children, the researchers warn.
Far from helping them to prepare and plan for pregnancy and parenthood, many public health programmes assume their needs are similar to the general population and require no special measures or provisions.
Professor Mark Hanson, of the University of Southampton, urged an initiative that engages parents to be and encourages them to be part of the solution.
Engaging future parents in leading healthier lives will not only promote their health later, but will give their children a healthier start to life, they say.
Professor Hanson said: 'The approach needed is both top down and bottom up, but even more importantly requires something in between which young people can help to create themselves.
'If at present many young people do not seem to care about their health or view it as a low priority, perhaps they have not been given clear information about what they can do to optimise their health for themselves and their children.
'All societies owe their adolescents the chance to make their future healthier.'