Epidural and spinal analgesia and labour.

Epidural and spinal analgesia for pain relief in labour are now commonplace. Adverse effects such as hypotension and toxicity to anaesthetic agents are well described and easily managed. The effects on obstetric outcome, however, have been unclear to both obstetricians and anaesthetists, but are important due to the large number of pregnancies involved. Efforts to define implications for mother and child have been frustrated by a relative lack of evidence derived from good quality, large randomized trials. Ethical and methodological difficulties together with an abundance of confounding factors have conspired to cause considerable difficulties for researchers in this area. Nevertheless, recent evidence has significantly advanced knowledge in the field and has implications for future practice.