Prime Minister's wife Cherie Blair is reported to be planning to have her fourth child by Caesarean section.

In most cases, Caesarean sections are carried out in emergencies when a natural delivery is either impossible, or might endanger the health of the child or mother.

However, in recent years an increasing number of women have chosen to opt for the procedure.

Elective Caesareans are seen as a way to avoid the pain associated with natural delivery, and also allow busy women to give birth at a time that is convenient to them.

'Too many Caesareans'

However, medical experts fear too many babies are now being delivered by Caesarean section in the UK.

The Royal College of Midwives produced statistics in November that showed that in some parts of the UK only 52% of deliveries were traditional births.

In the 1950s less than 3% of women were given Caesarean sections.

Speaking at the time, Frances Day-Stirk, head of midwifery affairs at the Royal College of Midwives, said the rise in Caesareans was "quite alarming".

She said: "Caesarean section has in some way become normal.

"Women sometimes don't worry awfully if they do have a Caesarean section, but of course it is a major surgical operation and it does carry attendant risks for the women and the baby."

Women who undergo a Caesarean section are six times more likely to die during childbirth than those who give birth naturally.

A Caesarean section is carried out under either general or local anaesthetic, and therefore there is a small risk of complications arising from the anaesthesia.

Women who undergo Caesareans also take longer to recover than those who give birth naturally. They may be more prone to bleeding, and even to infertility.

Research has also shown that babies born by Caesarean section tend to be at an increased risk for breathing difficulties than their vaginally born counterparts.

This is because natural birth gradually prepares a baby to breath by squeezing the lungs as the child passes through the birth canal.