Conventional operating tables will not support grossly overweight patients and scalpels and ultrasound scanners are unable to penetrate the deep layers of fat on many patients.

Dr Alan Mathers, clinical director of the Princess Royal Maternity Hospital in Glasgow, said he is struggling to cope with pregnant women, often weighing more than 20 stone, with the equipment at his disposal.

The obstetrician, who is also a government adviser, has revealed he is being forced to carry out caesarian sections on hospital beds because some women are too heavy for the operating tables.

Birth defects and complications are also being missed because ultrasound waves are unable to penetrate large fat deposits.

Mathers is now refusing to carry out routine gynaecological operations on some women because he believes surgery carries a great risk. He said Scottish hospitals will have to import longer scalpels, high-powered hoists and reinforced hospital beds from America, where two-thirds of the adult population is obese, and the market for the specialist medical equipment is worth $3bn (£1.7bn) a year.

His comments follow the publication of new research which reveals the number of obese pregnant women has doubled in the past decade.

The study, published in the British Journal of Obstetrics and Gynaecology, says a fifth of pregnant mothers are now obese and warns that their health and that of their children is being put at risk.

“I have sectioned at least 10 women in the past year who are over 130kilos — we have a super mother at least once a month,” said Mathers.

“We have junior doctors who are purely called in to help pull up the [abdominal] fat because the surgeon and their assistant are not enough to operate on these people.

“There are people who have advocated offering elective caesarians for these mega women, because it will be safer for them than an emergency at three o’clock in the morning.

“With some women you are looking at [having to cut through] 12 inches of fat before you get to the uterus. In America they have [surgical] instruments that are one and a half times longer than normal, just to operate on fat people. That equipment will be necessary in this country.”

In cases of severe obesity, birth defects may not be detected by ultrasound scans and there is a greater risk of pre-eclampsia, a condition of the placenta which is responsible for the deaths of around five women and 600 babies in the UK every year.

There is also concern that children of obese mother carry a higher risk of heart disease and diabetes in later life.

“If you are overweight or obese your risk of miscarriage goes up threefold and the risk of birth defects increases as does the risk of diabetes, pre-eclampsia, premature delivery, caesarian section and extreme birth weights,” said Professor Naveed Sattar, of the Glasgow University’s division of developmental medicine, who led the study.

Laura Cassidy, chair of the Scottish Ccommittee of the Royal College of Obstetricians and Gynaecologists, said: “Education on healthy diet and exercise and the risks associated with obesity should be part of preparation for pregnancy.”

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