This article contains posts and extracts from the UK Midwives and Consumers email list, a discussion group for people interested in midwifery in the UK. Open to midwives, students, mothers, and anyone interested in improving maternity services in UK. Posts in these archives express the views of the individual authors, and not those of the Association of Radical Midwives. Unless otherwise stated, the comments are personal experiences rather than evidence-based research.

Sterile water injections to relieve back pain

I seem to remember reading, or hearing about from some Swedish midwives, that injections of sterile water in or around the rhombus of Michaelis is actually very effective, and I believe that they quoted me some research in support of this contention. I have, naturally, lost the reference……

Pain Relief From Water Injections, from

A new trial from Sweden has shown that injections of sterile water under the skin are effective in relieving lower back pain in the first stage of labour

99 women with severe lower back pain were divided into three groups. One third had four injections 0.1 ml of sterile water intracutaneously (into the skin) in the lower back. Another third had four injections of 0.5 ml sterile water subcutaneously (under the skin). The final group had four injections of 0.1ml of saline subcutaneously. This was the “placebo” group. The injections were given during a contraction while the women breathed gas and oxygen.

The midwife caring for a woman did not know which treatment she had had. The women were asked to mark on a chart their pain levels before the injections, and at intervals afterwards – 10, 45 and 90 minutes. In all three groups pain had gone down 10 minutes after the injections – but it went down most in the first two groups, and least in the third, placebo group.

At 45 minutes pain was still markedly reduced in the first two groups but had gone back almost to base level for the placebo. At 90 minutes Pain levels had risen in Group 1 (though not to pre-treatment level) and had risen much less in Group 2. Group 3 had as much pain as they started with.

However, women found the injections for the placebo less painful than they found injections for Groups 1 and 2. The authors wanted to see if subcutaneous injections of water would be less painful than intracutaneous, but there seemed to be no difference.

AIMS Comment

There have been earlier studies showing that these injections can relieve back pain in labour. As so many women are unwilling to expose their babies to the effects of drugs, it is surprising that they are not more widely offered.

Jean Robinson

Reference: Martensson L and Wallin G, Labour pain treated with cutaneous injections of sterile water: a randomised controlled trial, Br J Ob Gyn, 1999; 106: 633-7.

I did the research appreciation part of my midwifery degree on ‘sterile water papules’ (SWP) and their efficacy – there are about 6 Swedish studies looking at thier effects – one at least being fairly large and rigorous. Scandinavian midwives use SWP regularly to relieve the excruciating back pain one sometimes gets in labour. Injecting sterile water subcutaneously into 4 places on the lower back, hurts like crazy for a few seconds, (like a beesting) then relieves back pain like magic for up to 1 1/2 hours! Minimal side effects. Presumed to work along the same lines as acupuncture.

The lecturer practitioner at the maternity unit I work out of was very unwilling to allow us to even contemplate using them with such flimsy evidence available! There are many US midwives using SWP also, and I first heard about them from Penny Simkin at the Midwifery Today Conference in London few years back -I also sent off for the video on where and how to do it, from a Canadian GP who finds SWP an effective remedy for back pain, with few side effects. Does anyone in UK actually use this method of pain relief?

Terri, Midwife, Devon, UK

Hi from Norway, where midwives do use sterile water papules for intractable back pain in labour. Not many women have this kind of pain but those who do will often have strikingly immediate relief from the injections. We use 0.1 ml of sterile water per papule (note: NOT saline) and inject it intracutaneously over the sacrum, using the smallest needle we can find. Two papules on either side, at upper and lower distal sacral borders approximately, and using the same needle and syringe for all. It’s easiest to ask the woman to point to the spot where pain is most intense and inject there. In this case, there is no discussion about whether to call it pain. It is PAIN, characterized by low-grade constant pain between contractions, switching to intolerable pain during them. Not fun for the woman or for her companions, including the midwife.

Pointers for success:
1) Do one injection on each side of the spine first, then do the other two, rather than doing both the right ones first or both left ones. Some women find them so uncomfortable that they will choose to stop after two injections and it works better if they aren’t on the same side.
2) Inject during a contraction, when the woman is in excruciating pain already. The intense stinging pain of the injection will generally have passed over into a sensation of warmth by the end of the contraction, and women with bad back labour need their intervals between contractions to recover more than most of us do.
3) Don’t bother using them if the woman is able to talk normally and detachedly about her back pain. She isn’t suffering enough to warrant the added discomfort of 4 wasp stings, which is the common term for them here, and with good reason.

Use your imagination and midwife resourcefulness in devising ways to create at least an appearance of informed choice in the situation, as just speaking to such women can be difficult. Having said all this I can personally attest to their usefulness, having used them myself in labour and for acute low back pain several years later. Since they don’t sedate the baby or the mother, they are also handy at home births. To my knowledge they do not reduce the likelihood of a spontaneous birth, and may even enhance it because many of these women would be candidates for epidurals otherwise.

Rachel Myr, midwife, Kristiansand, Norway

They have worked really well in my experience. They take away the constant back pain between contractions in addition to that pain superimposed on top of the contraction pain by an OP (posterior) presenting baby. So the woman can relax between contractions. I have not seen it work for non-OP labours.

It seemed to make turning techniques more effective too. Most of all it is a non-pharmacological technique that the midwife/ obnurse can administer as often as needed without bringing in the medical people.

Angela C.

I have used SWP several times but find it difficult to perform due to the severe pain the women experience during the procedure. In one case I was unable to complete the papules due to client refusal. In these few cases the swp were effective. At the last labour I used them, I used an ice pack on the area in a attempt to numb the area with little success. Any hints or tricks?


I was told that having two midwives perform the injections simultaneously will help reduce the time it takes (well obviously) and therefore the stinging.


Pain Relief From Water Injections, from (you can use the search engine on-site). 8.htm

UK Midwifery Archives: the cervix, covering cervical tears, and other issues.

Diagrams of technique:

AH updated 2 April 2001

1 Comment

  1. Alison

    I had this while in labour, performed by two midwives so a little less painful, I had gas and air while they injected. Absolutely the best pain relief and I would do it again.


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