Obese women are being given an anti-diabetes drug during pregnancy to stop their babies being born fat.
The trial – the first of its kind in the world – has been launched following evidence of a sharp rise in the number of so-called ‘sumo babies’.
Large babies are twice as likely to become overweight adults.
Researchers at the University of Edinburgh are giving 400 obese women the diabetes drug metformin during pregnancy. The drug should reduce the amount of energy reaching the baby in the womb.
Dr Fiona Denison of the Queen’s Medical Research Institute in Edinburgh told Sky News: “Metformin is a drug already taken by women during pregnancy if they have diabetes, so we know that it is safe.
“It works by reducing the mother’s blood glucose to more normal levels. We are hoping that will lead to a healthier outcome for mother and baby.”
More than 15% of pregnant women are now clinically obese.
They are more likely to develop diabetes and pre-eclampsia in pregnancy – and their babies are more prone to complications in the womb and to being stillborn.
Rebecca Fyfe was morbidly obese and developed dangerously high blood pressure while pregnant with her fifth and sixth children.
For her seventh, she lost four-and-a-half stone under the strict supervision of Slimming World – and she had no further health problems.
“As long as you are eating healthily, you are doing what’s better for your baby and yourself,” she said.
“When I had my other kids they had lots of sugar meals through me when they were in my womb. My seventh baby had the best nutrition of any of them.”
Figures from the NHS Information Centre show that last year there were 1,218 babies born weighing 5kg (11lbs) or more – a 30% rise in three years.
The Royal College of Obstetricians and Gynaecologists said the rise is so steep that treatment needs to be considered.
The college’s Patrick O’Brien said: “I don’t think anybody is saying this medication could replace the good advice of eating healthily and taking regular exercise.
“But there is no doubt that there is a significant proportion of women who start pregnancy obese and, at that stage, it is very difficult to lose weight.”
Nine hospitals around the UK are taking part in the trial. Results are not expected for at least two years.