Painkillers such as an epidural, as well as gas and air, are more effective than alternative approaches but have more side-effects, the review of 310 studies said.
Experts found epidural, combined spinal epidural (CSE) and inhaled gas and air managed pain effectively in labour.
CSEs relieved pain more quickly than traditional or low-dose epidurals, while epidurals resulted in higher rates of assisted delivery, such as forceps or ventouse extraction, and women were more likely to suffer problems such as high blood pressure and fever. Women taking gas and air were more likely to experience vomiting, nausea and dizziness, the study also found.
Meanwhile, being immersed in water, relaxation techniques, acupuncture, massage and non-opioid drugs, such as sedatives, were described as interventions that “may work” with fewer adverse effects.
Both relaxation and acupuncture decreased the use of forceps and ventouse (suction) in delivery, with acupuncture also decreasing the number of Caesareans.
But the team found there was “insufficient evidence” to make judgments on whether treatments such as hypnosis, sterile water injections, aromatherapy, Tens (transcutaneous electrical nerve stimulator) machines or opioids such as pethidine were more effective than placebos for managing pain in labour.
In comparison with other opioids, more women receiving pethidine experienced side- effects including drowsiness and nausea, the research from the Cochrane Collaboration found.
The experts, from universities including Liverpool, Warwick and Manchester, said: “Overall, women should feel free to choose whatever pain management they feel would help them most during labour.
“Women who choose non-drug pain management should feel free, if needed, to move on to a drug intervention.
“During pregnancy, women should be told about the benefits and potential adverse effects of different methods of pain control. Individual studies showed considerable variation in how outcomes such as pain intensity were measured and some important outcomes were rarely or never included – for example, sense of control in labour, breastfeeding, mother and baby interaction, costs and infant outcomes.”
Peter Brocklehurst, professor of women’s health and director of the Institute for Women’s Health at University College London, added: “This ‘review of reviews’ clearly shows that many methods of pain relief in labour, particularly non-drug methods such as massage and immersion in water, are not well researched.
“This does not mean that these methods don’t work – just that we don’t know because the research has not been done.”