For those interested... on the BBC website
news.bbc.co.uk/2/hi/health/4566682.stm
Calls to push 'do not cut labour'
Being told to push may not help a woman in labour
Urging a woman in labour to push makes little difference to how quickly she gives birth, and could cause health problems, research suggests.
University of Texas doctors found "coaching" was linked to a tiny reduction in the length of labour.
And when women were followed up, those who were coached were found to have an increased risk of bladder problems.
However the American Journal of Obstetrics and Gynaecology study only checked the women after three months.
We are moving away from active pushing in order to allow women to do their own thing
Dr Maggie Blott, obstetrician
The researchers from the University of Texas Southwestern Medical Center studied 320 women who were giving birth for the first time, had uncomplicated pregnancies and did not need epidural anaesthesia when they gave birth.
They focused on the length of the second stage of labour - when the cervix is fully dilated and the baby begins to descend.
Half the women were randomly assigned to be coached to push for 10 seconds during a contraction, while the rest were told to "do what comes naturally."
For those in the coaching group, the second stage of labour was shortened to an average of 46 minutes, compared with 59 minutes in the uncoached group.
'No alarm necessary'
Of the 320 women in the study, 128 returned for testing three months later.
Those who had been coached had smaller bladder capacity and a decreased "first urge to void" - the volume at which a woman wanted to pass urine.
However, the researchers stress that bladder function can return to normal over time, so this may not have been a permanent effect.
This report follows an earlier one that found a rise in pelvic-floor problems among coached women.
Dr Steven Bloom, an obstetrician and gynaecologist who led the research, said: "Often, it's best for the patient to do what's more comfortable for her."
Professor Kenneth Leveno, who also worked on the study, added: "Whether or not these functional changes have long-term consequences, I'm not ready to say.
"We don't want to alarm patients about this."
Dr Maggie Blott, an obstetrician at the Royal Victoria Infirmary in Newcastle, told the BBC News website: "People thought they were doing the right thing by encouraging women to actively push during labour.
"But we are moving away from active pushing in order to allow women to do their own thing.
"We try to have a passive second stage of labour and allow the baby's head to come down by itself before encouraging women to push.
"Pushing too much too soon causes the mother to get tired, increasing the risk she will need assistance during delivery, such as forceps.
"It can also cause the baby to get tired, which itself increases the risk of problems at birth."
She said it was possible that pushing too soon could increase the risk of bladder problems, but added other aspects of pregnancy and labour could also affect risk.