NEW YORK (Reuters Health) – Sterile water injected lateral to the lumbosacral spine in women with severe low back pain during labor substantially reduces pain and decreases the rate of Cesarean deliveries, according to a meta-analysis published in the August issue of BJOG: An International Journal of Obstetrics and Gynaecology.

“Up to one-third of women will…experience ‘back labor,’ which is thought to arise specifically from pressure of the fetal occipital bone against the maternal spine and pelvis when the fetus is in the suboptimal, occipital posterior position,” lead author Dr. Eileen K Hutton at McMaster University in Hamilton, Ontario, and associates note.

Because of the extreme, constant pain, epidural anesthesia/analgesia is the most common intervention for women with back labor. But as the authors point out, epidurals are not fail-safe: there can be complications, and they are not available in all hospitals.

Sterile water for pain management is usually administered as four 0.1 mL intracutaneous injections.

To investigate the therapeutic effect of the injections, the research team conducted a literature search that turned up 8 randomized, controlled trials (n = 828) comparing outcomes associated with sterile water injections with placebo (injection of isotonic saline), acupuncture, or transcutaneous electric nerve stimulation.

In all eight studies combined, sterile water cut the Caesarean section rate by half: 4.6% in the sterile water group and 9.9% in the comparison group (relative risk = 0.51).

The reports documented significant reductions in visual analog pain “TAJE scores of sterile water compared with all other interventions. The weighted mean differences were -26 at 10-30 minutes, -36 at 45-60 minutes, and -28 at 90-120 minutes.

Dr. Hutton’s team theorizes that the pain reduction from water injections may increase parasympathetic tone; enhance relaxation, which promotes fetal rotation to a more favorable position for vaginal delivery, and “decreases the urgency for a caesarean section and allowed for a long enough time for labor to progress normally.”