Researchers from Edinburgh and Aberdeen universities found that the risk of dying before the age of 55 was around 35 per cent higher in the offspring of obese women compared with those who had mothers of a normal weight.
The subjects also had a 29 per cent increased chance of being admitted to hospital for heart attacks, angina and stroke than children born to mothers of a normal weight.
Experts said the findings highlighted the importance of encouraging women to maintain a healthy weight before and during pregnancy.
The researchers, writing in the British Medical Journal, analysed data for 37,709 babies delivered between 1950 and 1976 who are now aged 34 to 61. Their mother’s weight was recorded during her first antenatal appointment in pregnancy.
The results showed that children were 35 per cent more likely to have suffered an early death from any cause by the age of 55 if their mother had been obese – classed as having a body mass index (BMI) of 30 or over. The offspring of women who were overweight – with a BMI between 25 and 30 – were found to be 10 per cent more likely to suffer an early death than those born to normal-weight mothers.
Among the mothers studied, 21 per cent (5,993 women) were overweight at their first antenatal appointment and 4 per cent (1,141) were obese.
Among the 37,709 children in the study, there were 6,551 deaths, with the leading cause being heart disease (24 per cent of deaths in men and 13 per cent in women). This was followed by cancer (26 per cent of deaths in men and 42 per cent in women).
With rates of obesity now much higher than when the group were studied – around one in five pregnant women are now obese – experts said the findings were concerning.
Professor Rebecca Reynolds, of the Tommy’s Centre for Maternal and Fetal Research at Edinburgh University, said: “This study highlights the need for more research to better understand and prevent the impact of obesity during pregnancy for offspring in later life and the biological processes at work.”
The study did not look at whether higher death rates were due to children of obese mothers being more likely to be overweight themselves, or whether they faced the same risks even if they were of a normal weight. Future research will look at this.
One theory is that being overweight in pregnancy may cause permanent changes in appetite control and energy metabolism in the unborn child, leading to a greater risk of heart problems later in life.
Dr Sohinee Bhattacharya, of the University of Aberdeen, added: “We need to find out how to help young women and their children control their weight better so that chronic disease risk is not transmitted from generation to generation.”
Jacqui Clinton, health campaigns director at Tommy’s, said: “If we are to tackle obesity in the UK, we need to start at conception and help mums to limit the impact of their weight on their babies.”