Doctors have been told to think again over how they view older mums
They have concluded that the higher levels of medical intervention are not necessarily linked to increased complications.
This could simply be due to the fact that doctors see older mothers as more high risk and so are more inclined to intervene in their births, even if it is not necessary.
There have been calls for doctors to reassess how they see older mothers.
They found that as the mother's age increased she was more likely to have higher levels of amniocentesis, Caesarean section, assisted delivery and induction.
Previous studies at the same hospital showed first-time mothers over the age of 40 are 14 times more likely to have an elective Caesarean than those under 30.
The latest study showed that the older mother was also more likely to have more than two scans, a stay of more than five days in hospital and have their baby admitted to a neonatal unit.
The authors said that there was evidence to suggest that uterine function could deteriorate with age.
But said it more likely that medical staff simply saw the age of the mother and then decided to intervene.
"The association may also reflect a preference for intervention among older women or their obstetricians, and these results would support that speculation."
Call for rethink
John Grant, editor-in-chief of the British Journal of Obstetrics and Gynaecology, where the study was published, said it was time for doctors to re-think their opinions of the older mum.
"How often have you seen 'Elderly primigravida' (first-time mother) written in the special features column of the maternity record?
"This will convey a subliminal message to the obstetrician and midwife caring for the woman in labour, which will colour their judgements, and lead inevitably to a Caesarean section.
"Where there are no tangible medical complications of pregnancy, the risks of childbirth in older women are no greater than in younger women."
Intervention 'unjustified'
Mr Peter Bowen-Simpkins, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists, agreed that women above 35 were more likely to be given medical intervention simply because of their age.
But he said older women were also more likely to ask the doctor for a Caesarean than the young mother.
"We probably do intervene more among older women and it probably is unjustified. It is probably the worry of the obstetrician than the fact the woman has problems."
"It could become a self-fulfilling prophecy."
She said older women often worried that they were at higher risk and said that it was important to strike a balance between informing patients and worrying them unnecessarily.
"One should always start from the premise that pregnancy is an entirely normal physiology."