Almost 20 per cent more women are having babies by Caesarean section than five years ago, a rise that has made campaigners "extremely concerned".

Caesareans increased from 18.2 per cent to 21.5 per cent of all births in the four years to 2001, with half of the 118,000 operations each year performed as emergencies.

The figures, released yesterday by the Department of Health, contrast sharply with the 1950s, when surgery accounted for less than 3 per cent of deliveries.

The National Childbirth Trust condemned the huge rise, warning that the Caesarean rate in Britain was now double that of Scandinavia and almost equal to the United States. Mary Newburn, a spokeswoman for the trust, said: "We are extremely concerned by these new statistics, particularly the relentless rise in emergency Caesareans accounting for more than half of these figures."

The trend has been blamed by some commentators on women said to be "too posh to push" demanding Caesarean deliveries. Other factors are a lack of full midwifery support to help women complete natural labour, a tendency to overdiagnose potential problems with the baby, less resistance among obstetricians to surgery and a fear of litigation if they do not intervene to halt a long labour.

Recent studies have suggested that one in three women who has a Caesarean has long-term fertility problems and consultants have admitted too many are being performed.

In response to concerns that women are agreeing to unnecessary Caesareans, the National Institute for Clinical Excellence will issue guidelines next year to hospitals on when they should be done.

Yvette Cooper, the Public Health minister, will also promise new national standards for maternity units today in a speech to the Royal College of Midwives. The standards will emphasise the need for women to have a choice on how they deliver their babies, including greater opportunity to choose a home birth.

Yesterday's maternity statistics showed that nearly half of all pregnant women now have assisted deliveries where they are induced, have Caesarean sections or require the use of instruments to give birth. Only 53 per cent of women have natural births where they go into labour spontaneously and deliver their babies without intervention.

Some 10 per cent of women have an elective Caesarean, 11 per cent emergency Caesareans and 11 per cent an instrumental delivery, most commonly by vacuum extraction rather than forceps.

One in five, or 21 per cent of women, had their labour induced either surgically, by drugs, or both. During delivery, one-third of women had an epidural, general or spinal anaesthetic while 14 per cent had an episiotomy.

About 88 per cent of babies were born between 37 and 41 weeks of gestation, with 5 per cent of births after 41 weeks and 7 per cent before 36 weeks. Of the premature births, 0.8 per cent were between 28 and 31 weeks and 0.5 per cent were before 28 weeks.

* The North-east has become the first region in England where more babies are born out of wedlock than to married couples, a National Statistics report published yesterday showed. The report found that 50.5 per cent of births in the region were to lone mothers and unmarried couples ­ 11 points above the national average.