Oxytocin antagonists for tocolysis in preterm labour -- a systematic review

Oxytocin antagonists have been shown to inhibit uterine contractions and delay preterm delivery. Our objective was to examine the clinical effectiveness and safety of oxytocin antagonists for tocolysis in preterm labour.

We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register and Science Citation Index using the following Medical Subject Headings and textwords: oxytocin (antagonists and inhibitors), atosiban, antocin, oxytocin antagonists, oxytocin receptor antagonists and oxytocin inhibitors. All randomised controlled trials that compared effectiveness and safety of atosiban with a placebo or another tocolytic in women with threatened or actual preterm labour were included. The primary outcome measure was the proportion of women undelivered by 48 hours from the commencement of treatment.

Six articles met the inclusion criteria - two compared atosiban to placebo and four atosiban to a beta-agonist. Meta-analysis showed a significant increase in the proportion of women undelivered by 48 hours in women receiving atosiban compared to placebo (RR 1.13, 95%CI 1.02, 1.26). When compared with beta-agonists, atosiban increased the proportion of women undelivered by 48 hours, but this trend did not reach statistical significance (RR 1.07, 95%CI 0.98, 1.17). Side effect profile was substantially better for atosiban compared to beta-agonists.

Oxytocin antagonists appear to be effective and safe for tocolysis in preterm labour.