A growing number of babies worldwide are at risk of brain damage or having a stroke, heart attack or asthma in adulthood because their mother was obese, health experts have warned.
Leading doctors said dangerously overweight mothers were passing on obesity to their children as the result of “a vicious cycle” in which excess weight can seriously affect the health of parents and their offspring.
Four studies published in the Lancet Diabetes and Endocrinology make clear that the risks of maternal obesity include stillbirth, dangerously high blood pressure in pregnant women, diabetes in the mother or child, and complications during childbirth.
The scale of obesity in women of childbearing age and the consequent dangers to health were so great that urgent action was needed to ensure women were a normal weight before they conceived, the authors say.
Mothers being very heavily overweight could lead to their children having autism or attention deficit hyperactivity disorder or developing cancer in later life, the researchers say.
British women have the highest rates of obesity in Europe. One in five women in the UK who became pregnant were already obese, while in England, 26% of 35- to 44-year-old women were obese in 2013, as were 18% of those aged 24-35.
Rates are even higher elsewhere. In the United States, 32% of women of peak childbearing age, between 20 and 39, were obese in 2011-12, and 60% of American women were either overweight or obese when they conceived, according to one study.
Prof Lesley Regan, the president of the Royal College of Obstetricians and Gynaecologists, which represents 14,000 doctors working in Britain and worldwide who specialise in childbirth and women’s health, said: “Obesity has reached pandemic proportions globally and its origins start in the womb. In the UK, the prevalence of obesity is over 25% in both women and men. Around one in five pregnant women are obese, increasing their risk of miscarriage, stillbirth and neonatal death as well as gestational diabetes, blood clots, pre-eclampsia, more complicated labours and severe bleeding after the birth.”
The international team of experts behind the studies said they feared that the problem, which is worst in developed countries, would escalate further because one in five (21%) women in the world are projected to be dangerously overweight by 2025.
One of the research papers, which have reviewed hundreds of previous obesity studies, warned: “The long-term effects of maternal obesity could have profound public health implications.” Another concluded that maternal obesity was spreading so fast, especially in western countries, that governments should start treating it as a global public health priority.
One of the research reviews, led by Prof Keith Godfrey of Southampton University, detailed the range of serious health problems that excess maternal weight could have on a child and pointed out that fathers’ weight could also increase the risks.
“Increasing evidence implicates maternal obesity as a major determinant of offspring health during childhood and later adult life,” the review states, adding that it heightened the child’s risk of obesity, coronary heart disease, stroke, type 2 diabetes and asthma. Maternal obesity could also lead to poorer cognitive performance and increased risk of neurodevelopmental disorders, including cerebral palsy.
An unborn child’s brain could be damaged because “obesity in pregnancy is associated with complex neuroendocrine, metabolic, immune and inflammatory changes, which probably affect foetal hormonal exposure and nutrient supply,” Godfrey’s paper explains.
The key lies in “epigenetic processes by which aspects of parental (both mother’s and father’s) lifestyle can affect the way the baby’s genes operate during development. These can change the person’s responses to the challenges of, for example, living in an ‘obesogenic’ environment,” it adds.
The National Institute for Health and Care Excellence advises women who may become pregnant to eat healthily, exercise for at least 30 minutes a day and try to maintain a healthy weight.
Each obese woman who gave birth in Britain cost the NHS £500 to £1,000 more than a mother of a normal weight, said Prof Rebecca Reynolds, of Edinburgh University.
However, the authors drew few firm conclusions in their search for ways to address and prevent maternal obesity and found limited evidence that specific interventions were effective.
“We know that there are going to be more and more obese people in years to come, so there will be passage of obesity from one generation to the next, even though no parent who is obese wants their child to suffer from it too,” said Prof Mark Hanson, of Southampton University, another co-author.
He recommended that overweight women be given more information and guidance from health professionals before they conceived or after they had given birth to help them lose weight, especially before they had any more children.
Bariatric surgery undertaken before an obese woman conceived could benefit both her and her baby’s health, the authors found, though anyone who has the operation should wait for up to 18 months afterwards before giving birth.
“Women who are overweight when entering pregnancy or who gain excess weight during pregnancy may well establish an inter-generational amplification of the obesity epidemic,” said Dr Tim Lobstein, director of policy at the World Obesity Federation.
“There is international agreement at United Nations level to halt the rising prevalence of obesity and diabetes across the globe. However, turning an ambitious target into practical action is proving elusive.
“There are well-recognised but well-embedded systemic problems to resolve, such as the increasingly commercialised food supply, the dominance of motorised transport, the development of dense and hazardous urban environments, or the enticements of sedentary screen-watching,” he said.
