Sterile water injection for labour pain: a systematic review and meta-analysis of randomised controlled trials

Up to one-third of labouring women will experience painful 'back labour'. Sterile water injected lateral to the lumbosacral spine is a simple and well-researched approach to this pain.

To determine if sterile water injection for low back pain compared to placebo or alternative therapy increased or decreased the rate of Caesarean section.

We performed a literature search with no language restriction in four databases: the Cochrane library, EMBASE (1980-2009), Ovid Medline (1950-2009) and CINAHL (1982-2009).

We included all randomised controlled trials (RCTs) of sterile water injection for labour pain that included outcomes of interest and original data.

We compared Caesarean section rates among women who received sterile water injection in labour with those who received either placebo treatment or another non-pharmacological treatment modality. Other outcomes included pain scores, use of regional analgesia and women's assessment of treatment. We used Revman 5 for the meta-analysis. Data were entered by one reviewer and independently cross-checked. Pooled outcomes were reported as Relative Risk (RR) or Weighted Mean Difference using Mantel-Haenszel fixed-effects model except when the I2 value >50% indicated significant heterogeneity in which case random-effects model was used.

We included eight RCTs. The Caesarean section rate was 4.6% in the sterile water injection group and 9.9% in the comparison group (n = 828) (RR 0.51, 95% CI: 0.30, 0.87).

We believe that a large RCT should be mounted to validate our findings regarding the impact of sterile water injections on mode of delivery.