Children born from obese women were 35 percent more likely to die prematurely in adulthood, according to a study Wednesday that warned of a growing epidemic.
Researchers in Scotland traced 37,709 children of 28,540 women who gave birth between 1950 and 1976.
The children were aged from 34 to 61 at the time of the study published in the online journal bmj.com. Researchers included the data of 6,551 children that had already died prior to the start of the study.
Of the mothers, 21 percent were overweight -- meaning a body mass index (BMI) or height-to-weight ratio of 25 to 29.9 -- and four percent obese, with a BMI of 30 or more, when they gave birth.
"The offspring of obese mothers were 35 percent and those of overweight women 11 percent more likely to die before the age of 55 years than those of normal-weight mothers," study co-author Rebecca Reynolds, professor of metabolic medicine at the University of Edinburgh, told AFP.
The team also found that the children of obese mothers were 42 percent more at risk of being admitted to hospital for heart disease as adults.
"Our results suggest that the intrauterine (womb) environment has a crucial and long-lasting effect on risk of premature mortality in offspring," the study said.
Other research has shown that conditions in the womb can cause lifelong body changes, which may affect such functions as appetite control and metabolism.
But post-birth factors like diet and exercise or a genetic propensity to be obese could not be ruled out as the cause of the children's health problems.
"Strategies to optimise weight before pregnancy are urgently required," wrote the team -- given that about one in five pregnant women in the UK are obese.
"We also need to consider giving good lifestyle advice to children of obese mothers and early monitoring of risk factors for heart disease such as high blood pressure, blood sugar, blood fats and smoking," added Reynolds.
According to the World Health Organization, more than 1.4 billion adults aged 20 and older were overweight in 2008 -- a figure that had nearly doubled since 1980.
More than a third of adults were overweight in 2008, and 11 percent obese. At least 2.8 million adults die every year as a result of weight-related health problems.
Worryingly, "only four percent of mothers in our study were obese, far less than current levels", added Reynolds.
"If the link between maternal obesity and adverse outcomes in her adult children persists as rates of maternal obesity rise then this could lead to an increase in premature deaths and heart problems."
Experts commenting on the study stressed the need for further research to confirm a direct, causal link between a woman's obesity and her child's risk of dying young.
"It is possible that the association results because the offspring of the obese mother is more likely to be obese themselves and therefore at increased risk of heart disease," said Susan Ozanne, a British Heart Foundation senior fellow.
Whatever the reason, the study emphasised the importance of a healthy weight, said cardiologist Tim Chico.
"The message of this study is clear: if a mother is overweight, it may be her children that pay the price."