One of the most interesting forms of pain relief in labour are sterile water injections.
As you might guess from the name, these are injections of sterile water, and they are used specifically to help relieve severe back pain.
In this blog post, I’m going to explain their use, and discuss the evidence on this topic.
I’m also going to explain why it’s hard to research these sorts of things, and how that can lead to controversy.
What are sterile water injections?
Sterile water injections aren’t quite the same as other types of injections.
That’s because the water is injected in very specific places JUST under the skin on a woman’s back, so that little blister-like bumps form.
The injections can be given by midwives, they don’t require a prescription*, and they don’t have the potential for side effects that pharmacological pain relief does. All of this means that they can easily be given at home or in birth centres.
This may be one of the reasons that some doctors are so against them, but we will come back to that.
* I do want to add that, while sterile water injections don’t require a prescription, this isn’t a home remedy that can be done by untrained people, partly because the sterile water needs to be medical grade. It is also very important that they are given in the correct place, or they won’t work, so some knowledge of anatomy is required.
A few more key facts
Sterile water injections are also described as sterile water blocks or papules or intradermal sterile water injections.
Usually, two or four injections are given. Using an insulin syringe with a small bore needle, 0.1 – 0.15cc of sterile water is injected intradermally into between one and four specific locations on the woman’s sacral area. See Lytzen et al (1989) or Lee et al (2013) for a technical description of the anatomical location of the injection points.)
In practical terms, this form of pain relief carries several advantages over epidurals and narcotics. Sterile water injections are far quicker and cheaper than an epidural. They don’t affect a woman’s ability to move, push or feel uterine sensations. They do not impact upon her baby’s well-being and no additional monitoring is required after administration.
On the other hand, while sterile water injections arguably carry fewer risks than epidurals, most women experience an incredibly intense stinging pain for somewhere between 30 and 90 seconds during and after administration. The fact that injections are involved means that there is a also very small chance that local infection or inflammation may develop.
A bit more on back labour and pain
One of the first things that midwives learned about sterile water injections, as Märtensson et al (2008) explain, is that, while sterile water injections can be labour-changing for women who are experiencing the intensity of a back labour, they do little or nothing to relieve the pain of contractions.
Midwives use the term ‘back labour’ to describe the situation where a woman feels all or most of the pain in her back, rather than in her uterus. In back labour, the pain may not go away between contractions. Melzack & Schafferlberg (1987) suggested that back labour is experienced by about 30 per cent of labouring women.
I already mentioned that sterile water injections are initially very painful, at least for most of us. However, many women who have had them say that, after the minute of intense stinging, the relief from the pain of back labour is immense. Women often feel that relief starting two or three minutes after the injections and it can last for up to a couple of hours.
The injections can be repeated more than once in labour if necessary.
A bit of history
The earliest paper that I have found describing the use of sterile water injections for pain relief was published in Denmark in 1981, where the authors were using these for the relief of pain from kidney stones (Bengtsson et al 1981).
Danish researchers also published some of the earliest studies of sterile water injections in labouring women (Trolle et al 1986, Lytzen et al 1989). Both of these papers are in Danish, but Trolle et al later published their results in English in the American Journal of Obstetrics and Gynecology (Trolle et al 1991).
Here’s their summary:
“To evaluate the analgesic effect of intradermal sterile water blocks, 272 women in labor complaining of severe low back pain were randomly assigned to treatment with either sterile water or saline solution blocks. Pain intensity was assessed on a visual analog scale, before the blocks were given and again 1 and 2 hours later. The groups were equal with regard to age, parity, fetal size, progression of labor, and initial pain scoring. Pain scoring 1 and 2 hours after the blocks were given showed a significantly higher degree of analgesia in the sterile water group. No adverse effects were noted, and patient acceptability was high.” (Trolle et al 1991).
Another early study into the use of sterile water injections in labour was conducted by researchers from Sweden. Ader et al (1990) published data on sterile water injections in a paper in Pain, and then in the Nursing Times (Ader et al 1991).
“Forty-five pregnant women in the first stage of labour presenting with lower back pain were randomized into 2 groups. One group received intracutaneous injections of sterile water in the lumbosacral region, while the other group was given corresponding subcutaneous injections of isotonic saline, regarded as a placebo treatment. In the group that received intracutaneous sterile water injections the mean VAS score was significantly more reduced compared to the placebo group at 10 min (P less than 0.001), 45 min (P less than 0.02), and at 90 min (P less than 0.05) after the treatment. The midwives’ blind estimation of the effectiveness of treatment was consistent with the VAS assessment. However, the requirement of pethidine (meperidine) was similar in the 2 groups. The analgesic method presented was found to be an effective treatment against lower back pain during the first stage of labour and it is speculated that the mode of action resembles acupuncture.” (Ader et al 1990).
The earliest published dissent that I have seen on this topic came from a Norwegian obstetrician (Tandberg 1990). Tandberg simultaneously argued that there was no evidence to support this method, and that it prolonged delivery. As I haven’t found any studies published which suggest that sterile water injections prolong delivery, I have to wonder if this comes from his personal observation. As the article is in Norwegian, which I don’t read, I have never been able to confirm whether this is the case.
My personal reflection
That doesn’t mean I think personal experience is invalid, by the way. Quite the opposite. I just want everyone to be honest about their beliefs, motives, and knowledge base. And ideally about the relationship between recommending certain things and their own income, job security or status. So with this in mind, I want to briefly explain my own experience, as this is a topic that I have been following for about three decades now.
I first encountered sterile water injections in 1994, when spending time with midwives in the USA.
At this point, I found the Scandinavian research and was aware of midwives in Scandinavia, the USA and Canada who were offering sterile water injections in practice. They may have been in use in other areas of the world as well but, upon my return to the UK, I couldn’t find anyone using this technique in practice there.
Over the next few years, I and some independent midwifery colleagues adopted sterile water injections into our toolkits, but it took much longer for these to be offered within mainstream maternity services in the UK.
In my experience, this was most commonly due to resistance from anaesthetists.
The challenge of researching simple tools
Since those early studies, the sterile water injection technique has become the subject of a few more research studies.
Most of these have been small, and this is likely due to the culture that we live in, and the nature of the intervention. Sterile water injections are simple, quick, inexpensive, and they can be given at home by midwives. They cannot be patented, they need no costly technology or equipment to administer, and there is no money to be made from them.
All of these things mean that it is extraordinarily difficult to get funding to carry out the kind of research study that would ‘prove’ their worth.
There is another issue with researching this kind of intervention. Ideally, studies should be ‘blinded’, so that neither the woman nor her caregiver know whether or not she is having the intervention (or drug). In many studies in maternity care, it’s just not possible to do this, because women can see and feel what they are having. The same thing applies to studies which look at things like method of birth (e.g. vaginal breech birth vs caesarean) or type of placental birth.
Jean Robinson had reviewed a study on sterile water injections in 1999 and commented that, “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” (21).
In some ways, however (and more on this below), it isn’t that surprising. When a person or professional group has decided that something is not for them, or might threaten their status, no amount of carefully collected data, trial evidence or pleas from those who desperately want to be able to access something is likely to change their minds.
The evidence base grows
Despite the barriers to researching sterile water injections, and the difficulty that researchers have in being able to carry out large studies that are comparable to those which evaluate medical interventions, a number of studies have been published over the years.
For example, the author of a 2008 systematic review found that:
“…sterile water injections induce a statistically significant, dramatic analgesic effect on the low back pain experienced by women during labour; lasting from 10min and up to 2h post-administration … [They] have proved to be a justifiable alternative to the use of narcotics for birthing women and their midwives who are concerned about unwanted side effects for mother and baby. Their effect has been described as powerful, rapid and effective, with the potential to decrease or delay the use of epidural anaesthesia.” (Fogarty 2008: 162).
Fogarty (2008) urged Australian midwives to champion the use of sterile water injections for women.
Around the same time, a survey of 450 Nurse-Midwives working in the US revealed that just over a quarter of them were offering this form of pain relief (Märtensson et al 2008). The same study showed that many more US midwives who hadn’t yet begun to use them said they were interested in learning more.
Use of sterile water injections in the UK, which had begun with independent midwives, was now growing, although it wasn’t common.
The Cochrane review
In 2012, Cochrane reviewers looked at the evidence in this area. Here’s what they found:
“We included seven studies, with 766 participants: four used intracutaneous injections, two subcutaneous, and one both. All reported on low back pain in labour only. Methodological quality was good, but four studies were at high risk of bias due to small size of treatment groups, incomplete outcome data, and performance bias. All studies reported treatment group mean or median scores, finding greater reduction in pain for sterile water. However, failure to demonstrate a normal distribution for pain intensity or relief, and use of different scales, meant meta-analysis was inappropriate. No study reported primary dichotomous efficacy outcomes. One reported the number self-scoring 4/10 cm or more reduction in pain; significantly more had this outcome with sterile water (50% to 60%) than with placebo (20% to 25%).There was no significant difference between sterile water and saline for rates of caesarean section (risk ratio (RR) 0.58, 95% confidence interval (CI) 0.33 to 1.02), instrumental delivery (RR 1.31, 95% CI 0.79 to 2.18), rescue analgesia (RR 0.86, 95% CI 0.44 to 1.69), timing of delivery, or Apgar scores. Two studies reported that more women treated with sterile water would request the same analgesia in future. No study reported on women’s satisfaction with pain relief, women’s sense of control in labour, women’s satisfaction with the childbirth experience, mother/baby interaction, rates of breastfeeding, maternal morbidity, infant long-term outcomes, or cost. No adverse events were reported other than transient pain with injection, which was worse with sterile water.” (Derry et al 2012)
The authors concluded that:
“The outcomes reported severely limit conclusions for clinical practice. We found little robust evidence that sterile water is effective for low back or any other labour pain. Neither did we find any difference in delivery or other maternal or fetal outcomes. Further large, methodologically rigorous studies are required to determine the efficacy of sterile water to relieve pain in labour.” (Derry et al 2012)
I don’t think these points are unfair. As I mentioned above, such studies are really hard to carry out and get funded. But it’s frustrating that such reviews don’t note the very unlevel playing field that exists between costly pharmaceutical treatments and inexpensive, simple remedies. I’ve also written about this in relation to holistic therapies.
It’s also unfortunate that this Cochrane review hasn’t been updated, because some larger studies have been carried out since it was published. For example, Australian researchers have carried out a small randomised controlled trial (Lee et al 2013), a study of women’s experiences of sterile water injections (Lee et al 2017) and a study of midwives’ experiences (Lee et al 2017b). They have further research planned (Lee et al 2022).
The NICE review
Many women, midwives and birth workers were delighted when NICE published an evidence review for sterile water injections in September 2023.
They did look at the more recent evidence, and concluded that:
“…the majority of the evidence showed that sterile water injections had an important benefit in terms of general labour pain, back pain during labour and satisfaction. There was no evidence to suggest a difference in mode of birth, or use of other pharmacological analgesia.” (NICE 2023).
“When compared to dry injections, sterile water injections at 0.4ml and 2ml doses showed an important benefit on general labour pains and back pains during labour. This was seen from 10 minutes up to 180 minutes, with the exception of 2ml dose at 10 minutes where there was no evidence of an important difference.” (NICE 2023).
The review did highlight that the evidence isn’t all of high quality, which isn’t an unreasonable comment. I have already explained above that it is very difficult to get the funding to do large, high-quality research studies. I will also note (and I am coming back to this as well) that there are many areas of maternity care where the research isn’t of high quality. Yet this doesn’t stop NICE, other public health bodies and individual practitioners making recommendations, especially when it comes to the offering of obstetric intervention.
A more reasonable stance
The NICE review takes what I and many others think to be a reasonable stance. They acknowledge that the evidence isn’t strong, but conclude that women should be able to choose to have sterile water injections if they so wish.
“The committee discussed the evidence around sterile water injections and agreed to make recommendations supporting the use of sterile water injections for women experiencing back pain during labour. They agreed that the evidence on sterile water injections when compared with saline and dry injections were the most informative and supported these recommendations. They discussed concerns over the quality and paucity of evidence between comparisons with standard care and other non-pharmacological pain reliving strategies and agreed that this evidence was less useful in helping them make recommendations. The committee had concerns over the quality of the evidence, and therefore agreed they could not make a strong recommendation. They discussed that women should be given the option to choose sterile water injections as a method of analgesia for back pain, and in practice they would have the option to request different analgesia if sterile water injections were not an effective pain relieving strategy for them.” (NICE 2023).
“The committee discussed that there was some evidence showing a benefit on general labour pains, but agreed there was not enough evidence to support a recommendation and as most of the evidence of benefit was for back pain, they agreed to recommend sterile water injection for back pain during labour only.” (NICE 2023).
So it’s all good, yes?
As I write above, this review was welcomed by women, midwives and birth workers.
But I feel I also need to share the fact that some doctors are still questioning this, and trying to stop women having access to low-tech strategies for managing pain in labour.
In June 2024, doctors wrote to the British Medical Journal protesting the inclusion of sterile water injections for back pain in labour in the NICE intrapartum care guideline (Muraca et al 2024).
In a nutshell, they are questioning the quality of the evidence.
Again, yes, the evidence could be better, but there IS evidence of benefit, and it’s incredibly hard to conduct the kind of research called for here in a culture that is so focused on profit.
But there is also a wider point that is more important, and which I want to share in the context of this conversation.
Make it make sense
If we are going to set a standard for evidence quality, then that standard needs to apply across the board.
To ALL interventions.
Somewhat ironically, Muraca et al‘s (2024) letter was published just days after another study about a potential benefit of epidurals had made headlines which weren’t supported by the findings.
But it’s incongruous and intellectually dishonest to promote epidurals one week, based on not-very-brilliant evidence, and then the very next week say that sterile water injections shouldn’t be offered because the evidence base isn’t very brilliant.
If the quality of evidence for sterile water injections is being questioned, then I hope this means that we can look forward to the same sort of questioning being applied to the obstetric interventions that women are being told they need (and sometimes being coerced into having) every day.
(Don’t hold your breath.)
If doctors and policymakers applied the same quality requirement for evidence before recommending medical interventions such as induction of labour, syntocinon administration, and poorly-evidenced ‘care’ bundles, we would see better long-term outcomes, less birth trauma, and happier and healthier women and babies.
Back to sterile water injections
But back to sterile water injections.
Some women asked me at the time whether the letter (which I discussed on social media) meant that they should avoid sterile water injections.
And my answer is this. It’s not up to me to recommend what will or won’t be right for you. But that’s because I’m not you. Only you can decide what’s right for you, and I see my job as being to explain the evidence within the context of the wider issues, so that you can understand the topic and make the decisions that are right for you. I have several books that can help you with this in different areas.
But is this letter or the complaining from a small minority of our medical colleagues a reason to avoid sterile water injections?
I would say absolutely not.
Here’s the bigger picture
There are many things that have helped women in labour for millenia. Many of them haven’t been researched in randomised controlled trials, and will never be the subject of the kind of robust research that some doctors are calling for.
(Even though the same doctors don’t always have the same kind of evidence to support the things that they are promoting. It has long been a case of ‘one rule for doctors, and another for midwives, women and those who support them’.)
I can’t advise you whether or not sterile water injections are right for you. Only you can make that decision.
But I can tell you that I have seen them work well (though don’t forget the downside of that initial sting), and that I haven’t seen any evidence to suggest they cause harm. Unlike some pharmacological forms of pain relief, which carry both potential advantages and potential risks.
This blog post also contains many links and a reference list, so you can research further, and find out more.
And if you’d like to better understand some of the issues and get some practical tools for helping you make the decisions that are right for you, this book will help:
References
Ader L, Hansson B, Wallin G (1991). Injections of sterile water for labour pain. Nurs Times 87(6):53.
Ader L, Hansson B, Wallin G (1990). Parturition pain treated by intracutaneous injections of sterile water. Pain. 41(2):133-138.
Bengtsson J, Worning AM, Gertz J et al (1981). Urolithiasissmerter behandlet med intrakutane steriltvandspapler. En klinisk kontrolleret dobbeltblind undersøgelse [Pain due to urolithiasis treated by intracutaneous injection of sterile water. A clinically controlled double-blind study]. Ugeskr Laeger. 143(51):3463-5. Danish.
Derry S, Straube S, Moore RA et al (2012). Intracutaneous or subcutaneous sterile water injection compared with blinded controls for pain management in labour. Cochrane Database Syst Rev. 2012 Jan 18;1:CD009107. doi: 10.1002/14651858.CD009107.pub2. PMID: 22258999.
Fogarty V (2008). Intradermal sterile water injections for the relief of low back pain in labour – A systematic review of the literature. Women and Birth. 21(4): 157-163.
Lee N, Webster J, Beckmann M et al (2013). Comparison of a single vs. a four intradermal sterile water injection for relief of lower back pain for women in labour: A randomised controlled trial. Midwifery 29(6): 585-591.
Lee N, Kildea S, Stapleton H (2017a). “No pain, no gain”: The experience of women using sterile water injections. Women Birth. 30(2):153-158.
Lee N, Kildea S, Stapleton H (2017b). ‘Tough love’: The experiences of midwives giving women sterile water injections for the relief of back pain in labour. Midwifery. 53:80-86.
Lee N, Gao Y, Mårtensson LB et al (2022). Sterile water injections for relief of labour pain (the SATURN trial): study protocol for a randomised controlled trial. Trials 23, 155 (2022).
Lytzen T, Cederberg L, Möller-Nielsen J (1989). Relief Of Low Back Pain In Labor By Using Intracutaneous Nerve Stimulation (Ins) With Sterile Water Papules. Acta Obstetricia et Gynecologica Scandinavica, 68: 341-343.
Märtensson L, McSwiggin M, Mercer JS (2008). US Midwives’ Knowledge and Use of Sterile Water Injections for Labor Pain. Journal of Midwifery and Women’s Health. 53(2):115-122.
Melzack R and Schafferlberg, D. (1987) Low back pain during labour. American Journal of Obstetrics and Gynecology. 156: 901-905.
Muraca GM, Kramer JLK, Butwick AJ (2024). Sterile water injections for back pain in labour. BMJ 385: q1187.
Robinson J (1999). Pain Relief From Water Injections. AIMS Journal 11 (2): 21.
Tandberg A (1990). Intrakutane injeksjoner med sterilt vann som analgesi ved fødsler [Intracutaneous injections of sterile water as analgesia during labor]. Tidsskr Nor Laegeforen. 110(18):2349-50. Norwegian.
Trolle GB, Hvidman LE, Guldholt IS (1986). Laendesmerter hos fødende behandlet med steriltvandspapler [Lumbar pain in parturient women treated with sterile water injections]. Ugeskr Laeger. 148(20):1200-2. Danish.
Trolle B, Møller M, Kronborg H (1991). The effect of sterile water blocks on low back labor pain. Am J Obstet Gynecol. 164(5 Pt 1):1277-81.
Wickham S (2009). Sterile water blocks: is it time to talk? TPM 12(1):43.
About the Author: Dr Sara Wickham is an author, speaker, and researcher specialising in pregnancy, birth and maternity care. Her work focuses on evidence-based, woman-centred information and informed decision-making, drawing on more than 30 years of midwifery knowledge and experience.
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