Labour pain and methods to relieve it are major concerns for pregnant women, healthcare workers and the general public. These concerns have implications for the course of labour, for the quality of maternal and infant outcomes as well as for the costs of obstetric health care.
Women in labour who need pain relief should not only have access to invasive methods such as an epidural, which may have considerable side effects, but other means of pain relief as well. Futhermore, even in hospitals with full-time obstetric anaesthesia coverage no one may be available to give an epidural, and in primary care, invasive methods for pain relief are not available at all.
All women in labour should have the opportunity to choose some non-invasive method of relatively effective and safe analgesia at short notice when they wish it during labour. Inhaled pain relief, such as nitrous oxide and some flurane derivatives, may be a very useful additional method for pain relief. It is relatively easy to administer, can be started in less than a minute, and become effective within a minute. Nitrous oxide is more widely known and used as inhaled pain relief during labour compared to flurane derivatives, probably due to the availability of safe equipment, no pungent smell and the ease of administration.
In this review of 26 randomised controlled trials of 2959 women, the effectiveness and safety of inhaled analgesia as pain relief for women in labour were studied. It was found that inhaled analgesia may help relieve pain during labour but women have to be informed about the side effects, such as nausea, vomiting, dizziness and drowsiness.
Inhaled analgesia may help relieve labour pain without adversely increasing operative delivery rates (forceps or vacuum extraction, caesarian section), or affecting neonatal well being. Flurane derivatives were found to be slightly more effective than nitrous oxide for the reduction of pain and for pain relief although nitrous oxide also helped to relieve pain when compared with no treatment.
Women who used nitrous oxide were more likely to experience nausea compared with flurane derivatives. When nitrous oxide was compared with no treatment or placebo, nitrous oxide resulted in side effects such as nausea, vomiting, dizziness and drowsiness.