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Back pain in labor can be excruciating, and it may not let up between contractions. For women hoping to avoid an epidural, a labor that’s a pain in the back can put paid to that plan. A large study has found that a long-used midwifery technique, water injections in small amounts just under the skin at four points on the lower back, offers an effective alternative to an epidural. Let’s review what the study found, how people think water injections work, and finish up with a take-away from the study’s findings.
What did the study find?
Women experiencing severe back pain in labor were assigned to receive either the treatment, injection of pure water, which is irritating, or a placebo injection of saline solution, that is, water containing salt in the same amount as bodily fluids, which is not. As measured on a scale of one to ten, women receiving the pure water were more likely to report substantial reduction in back pain lasting 90 minutes or more compared with women receiving the placebo saline injection. More women rated the pure water injection as “very” or “rather” effective, more were likely to say they were “very satisfied,” and fewer were likely to say they were “dissatisfied” or “very dissatisfied.” They were also more likely to say they would choose the same treatment again and that they would recommend it to other women. (If you want the details, scroll down to “Taking a Deeper Dive.”) Other than a short-lived stinging pain at injection, pure water injection had no adverse effects on women or their babies.
How might water injections under the skin relieve back pain?
You may be wondering why injecting a small amount of water under the skin would relieve back pain. One explanation is the “gate control” theory of pain transmission. According to this theory, pain transmitted by nerves in the skin in response to the sterile water injection close a “gate” in the spinal cord, thereby blocking internal (visceral) nerves from transmitting the pain of backache to the brain. That wouldn’t explain why pain relief is so long-lasting, but another theory is that, as with acupuncture, the body releases endorphins, the body’s natural pain relievers, in response to pain. As this study confirms, though, whatever the reason, the treatment works.
To make an informed decision about any treatment, you need to know what’s involved, its benefits and harms, and the benefits and harms of alternative treatments. We’ve covered what’s involved in administering water injections in this post’s first paragraph, so, what do we know about the pros and cons of water injections and how they compare with epidural analgesia?
On the plus side, pure water injections . . .
On the minus side they . . .
If your plan is to avoid epidural analgesia or you are planning a home or birth center birth, you may wish to ask whether sterile water injection would be an option should you develop severe backache. If your care providers aren’t familiar with the technique and would like to know more, the study is downloadable for free.
Taking a Deeper Dive
What are the details of the study?
In a study conducted in 16 hospitals, 1147 women experiencing severe back pain in labor (rated their back pain at 7 or above on a scale of 1 to 10) were randomly allocated, that is, assigned by chance, to receive either the treatment, an injection of pure water, or a placebo injection of salt water. Randomized controlled trials produce the strongest evidence because the design reduces the odds of factors unrelated to treatment influencing results.
Women receiving the treatment were more likely to report at least a 30% reduction in pain at 30 minutes (61% vs. 31%), 60 minutes (53% vs. 30%), and 90 minutes (46% vs. 25%) after pure water injection compared with women receiving the saline placebo. They were also more likely to report a reduction of at least 50% at those same time intervals (43% vs. 18% at 30 minutes, 37% vs. 20% at 60 minutes, and 34% vs. 17% at 90 minutes).
More women rated the pure water injection as “very” or “rather” effective (67% vs. 41%), more were likely to say they were “very satisfied” (34% vs. 17%), and fewer were likely to say they were “dissatisfied” or “very dissatisfied” (30% vs. 49%). They were also more likely to say they would choose the same treatment again (60% vs. 53%) and that they would recommend it to other women (72% vs. 61%).
Other than short-lived stinging pain with injection of pure water compared with salt water, no adverse effects were found in mothers or babies.
Gizzo S, Di Gangi S, Noventa M, et al. Women’s choice of positions during labour: return to the past or a modern way to give birth? A cohort study in Italy. Biomed Res Int 2014;2014:638093.
Lawrence A, Lewis L, Hofmeyr GJ, et al. Maternal positions and mobility during first stage labour. Cochrane Database Syst Rev 2013;10:CD003934.