Nonnenmacher 2009.

Methods	Prospective, randomised, controlled trial.
Participants	105 women > 18 years at 24‐33 completed weeks' gestation, ≥ 4 contractions every 30 min lasting ≥ 30 seconds, opening of the uterine orifice and/or an ultrasound‐verified residual cervix < 25 mm for single pregnancies and < 20 mm for multiple pregnancies. Exclusion criteria: heavy vaginal bleeding, severe pre‐eclampsia, extreme high blood pressure, temperature > 37.5ºC, fetal or placental abnormalities (e.g. chorioamnionitis, premature separation of the placenta, delayed intrauterine growth, fetus in a stressed state, intrauterine fetal death, severe dysplasia, severe maternal health problems, e.g. heart or circulatory disease, hyperthyroidism, alcohol or drug abuse and hypersensitivity to any component of the study drug.
Interventions	ORA group: atosiban. Bolus injection of 6.75 mg, then 18 mg/h for 3 h (i.v.) and thereafter 6 mg/h up to 45 h. Control group: fenoterol. 2 x 0.5 mg ampoules in 50 mL NaCl solution by pulsatile administration with an allowance of 1000 IU heparin. Initial dose 1.5 µg/min or 2.0 µg/min; if no improvement was seen after 30 min, the dose was incrementally increased to 3.5 µg/min. At cessation of labour the dose was reduced within 3‐6 h to 1 µg/min and 0.5 µg/min.
Outcomes	Percentage of women who experienced a prolongation of pregnancy. Primary endpoints: proportion of women who experienced a prolongation of pregnancy of 48 h and 7 days. Secondary endpoints: time to reduction of contractions to ≤ 1/30min, maternal and fetal side effects and neonatal outcomes.
Notes	Publication has been translated to English by the Cochrane Pregnancy and Childbirth Group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Unable to determine how randomisation was performed.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Unblinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Unlikely.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All women randomised were included in analysis.
Selective reporting (reporting bias)	Low risk	All outcomes were reported as expected.
Other bias	Low risk	None apparent.