Last updated at 08:33 02 January 2008
Mothers who have a Caesarean birth more than triple their risk of needing a hysterectomy after their next pregnancy, British researchers warn today.
Doctors say the surgical scar significantly boosts the chances of complications which can rob mothers of their chance to have more children.
The biggest study of its kind found one in 30,000 women having their first birth normally had a hysterectomy to control severe bleeding.
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Risks: Mothers who have had a Caesarean birth face 3.5 times the possibility of needing a hysterectomy after their next pregnancy
But one in every 1,300 women who had one previous Caesarean birth had her womb removed and in women with two or more Caesareans, the risk rose dramatically to one in 220 women.
Now experts are calling for extra attention to be paid to women with a history of Caesarean delivery, who should be made fully aware of the risk of infertility.
The study was carried out by researchers at the National Perinatal Epidemiology Unit (NPEU) based at Oxford University.
The latest findings are likely to raise fresh concerns about the soaring numbers of Caesareans among mothers "too posh to push", who want the convenience of a planned operation.
Experts are trying to cut the rate of Caesarean births which is up to one in three in some parts of the country - twice the 15 per cent recommended by the World Health Organisation.
Fewer than half of all mothers in the UK have a completely natural birth, with 55 per cent requiring forceps, ventouse (suction cap) or a Caesarean to assist with delivery.
Although emergency Caesarean births can be life-saving, planned surgery is recognised as riskier for mothers because they are more likely to develop complications and spend twice as long in hospital as women having a natural delivery.
There are also risks to infants delivered by Caesarean who are more likely to suffer breathing difficulties.
The latest study, led by Dr Marian Knight, honorary consultant in public health at the NPEU, used data about all 775,000 women who gave birth between February 2005 and February 2006 in the UK, and those who had a hysterectomy following childbirth.
The information is collected using a national surveillance system developed to study rare disorders of pregnancy, particularly "near-miss" events.
It found that a history of Caesarean delivery meant the mother was more at risk of needing a hysterectomy with each subsequent pregnancy.
Women with twin pregnancies, older mothers and those who already had three or more children were also at a higher risk of needing a hysterectomy.
The majority of hysterectomy operations were performed when the placenta - the life support system keeping the baby supplied with nutrients and blood - had grown abnormally.
It may have grown too low in the womb - known as placenta previa - or through the wall of the womb.
Another reason for the womb to be removed was its failure to contract properly once the baby was born.
Dr Knight said women should understand Caesarean section is "not a risk-free procedure".
She said: "It is essential that women who have had a previous delivery by caesarean section are assessed in the last third of pregnancy to determine whether the placenta has grown in an abnormal site.
"This way, we can help to identify women who are at risk of severe bleeding so that measures can be taken to try to prevent it.
"Despite the risks, there are many circumstances in which delivery by caesarean section will still be the safest option for both mother and baby" she added.
Consultant obstetrician Professor James Walker, spokesman for the Royal College of Obstetricians and Gynaecologists, said having a Caesarean could lead to problems in a following pregnancy because the placenta, or afterbirth, may grow into the scar.
The scar also affects the development of the womb lining, which may lead to excessive bleeding during delivery that can only be stopped by a hysterectomy.
Prof Walker said: "A first Caesarean is a safe procedure but it leaves a scar that can increase the risks next time.
"There is no reason for women to be frightened, the numbers having a hysterectomy are still low, but it's a factor that should be taken into account when discussing the balance of risks and benefits for Caesareans."