Pain relief options

Sterile water injections (SWIs)

How are SWIs given?

  • the procedure involves a small amount of sterile water (0.01–0.02 mL) injected under the skin at four locations on the lower back (sacrum)
  • the injections cause a brief but intense stinging sensation, that lasts for about 30 seconds and then wears off completely
  • to distract from the stinging sensation, the injections are done during a contraction by two midwives.

How can SWIs help during labour?

During labour, SWIs provide effective pain relief for up to 85% of women with back pain and can last for up to two hours.

SWIs have a number of advantages, they:

  • often have an immediate effect
  • have no effect on the mother's state of consciousness
  • have no effect on baby
  • do not limit mobility
  • do not adversely affect labour progress
  • are a simple procedure that can be administered by your midwife and can be repeated as needed.

A diagram showing a person’s lower back with four marks showing the locations SWIs are given.

More information: Pregnancy, Birth and Baby – Non-medical pain relief during labour

In this guide

  1. Managing pain in labour
  2. Transcutaneous electrical nerve stimulation (TENS)
  3. Sterile water injections (SWIs)
  4. Nitrous oxide (gas)
  5. Morphine
  6. Epidurals

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