Giving women control over their own epidurals during labour could reduce the need for medical intervention, say researchers.
The spinal pain relief is normally given at a steady rate, but some women are offered a button to push when they feel they need an extra dose.
The study, presented at a US conference, suggested that women using the devices used a less anaesthetic, with fewer forceps deliveries.
In the UK, the system is available in approximately one fifth of hospitals.
Approximately 40% of women giving birth in the UK have an epidural - which uses anaesthetic delivered directly into the spine to numb the lower half of the body.
One of the downsides is a higher rate of "instrumental deliveries" - in which doctors need to use forceps or a ventouse to help deliver the baby's head.
The study at the Long Beach Memorial Medical Center in California compared the experience of 270 women, two-thirds of whom received a steady infusion of drugs, which the other third was given a hand-held controller so drugs could be delivered when needed.
The women could not keep requesting extra pain relief, as each press of the button delivered a dose, then "locked out" further presses for a set period.
While there were no differences in the duration of labour, those using "patient-controlled epidural analgesia" (PCEA) used approximately 30% less anaesthetic.
Patient satisfaction was roughly the same, although women self-administering drugs did report more pain during the final stage of labour.
In addition, there was some evidence that instrumental deliveries were fewer in the PCEA group.
Cost a factor
Dr Michael Haydon, one of the authors of the research, said that attention should now turn to offering extra doses in the final stages of labour, or even developing technology which could automate the process and detect increasing pain levels.
Dr Elizabeth McGrady, a honorary clinical lecturer in anaesthetics at Glasgow University, said that the financial cost of buying new anaesthetic pumps were one reason it was not available in every hospital.
She said: "The technique reduces the need for anaesthetic which in turn reduces the need for forceps delivery - and it gives women a feeling of control.
"The question is whether the small clinical advantages are enough to justify the cost of new equipment and staff training."
Patrick O'Brien, a consultant obstetrician and spokesman for the Royal College of Obstetricians, said that while the move to "mobile" epidurals - offering similar pain relief with fewer complications - had "revolutionised" maternity care, it was less clear whether there was a need for the patient-driven pumps.
He said: "Most women seem to be very happy with the 'mobile' epidurals, and while I do like the principle that the woman is placed in control, I'm not sure it would make a huge difference to the experience."
The research was presented at the Society for Fetal Maternal Medicine Annual Meeting in San Francisco.