Despite World Health Organisation advice that as few as 10 per cent of births should be Caesarean sections, some hospitals are delivering up to 30 per cent of babies in this way.

Now midwives, gynaecologists and obstetricians have gathered at a conference in London to find out why the rate is so high.

One theory is the rise of women who are "too posh to push" and see a Caesarean section as an easy way of giving birth.

But experts point out that a Caesarean is major surgery, with risks, and should only be performed if the risks are justified.

Frances Day-Stirk, head of midwifery affairs at the Royal College of Midwives said: "Caesarean sections involve major abdominal surgery and, as with any major operation, carry definite risks of morbidity and mortality.

"To justify taking these risks there have to be positive clinical benefits to mother and child."

The conference will see members of the National Childbirth Trust, the Royal College of Midwives and the Royal College of Obstetricans and Gynaecologists gather to discuss why the rate is on the increase.

Other issues will include:

• why average rates vary from 13 per cent in Cornwall to 26 per cent in Surrey
• how maternity services can meet the needs of the rising number of women having such surgery
• how the NHS can cope with the higher cost of Caesareans becoming more routine.