Lin 2009.

Methods	Randomised, unblinded, controlled trial.
Participants	45 women with spontaneous preterm labour (duration of contractions 30 sec or more at a rate of ≥ 4/min, cervical dilation of 0‐3 cm and cervical effacement of ≥ 50%) at 24‐33 weeks' gestation. Exclusion criteria: multiple pregnancy (> twins), ruptured membranes, major vaginal bleeding (continuous vaginal bleeding or bleeding volume > 100 mL); pre‐eclampsia or hypertension (blood pressure > 140/90 mmHg), temperature > 37.5°C, urinary tract infection, fetal placental/amniotic abnormalities (e.g. major fetal anomalies, chorioamnionitis, polyhydramnios, fetal growth restriction or placenta praevia), serious maternal disease (e.g. cardiovascular disease, hyperthyroidism, diabetes, pheochromocytoma or asthma), contraindications to the use of betamimetics, alcohol or drug abuse, exposure to NSAID tocolytic drugs < 12 hr of study entry, hypersensitivity to any component of the study drugs and participation in an clinical trial < 1 month.
Interventions	ORA group: atosiban. A bolus dose (6.75 mg in 0.9 mL saline, i.v.) followed by infusion at 18 mg/h (300 µg/min) for 3 h and then 6 mg/h (100 µg/min) for 15 h. Control group: ritodrine. Initial infusion of 20 mL/h (66.6 µg/min, i.v.) and increased by 10 mL/h (33.3 µg/min) every 10‐30 min, until the desirable uterine response (uterine quiescence < 4 contractions/h) was obtained. Both atosiban and ritodrine was administered for maximum 18 h during first treatment.
Outcomes	Compare the tocolytic efficacy and safety profile of atosiban and ritodrine in an Asian population. Monitoring of adverse events, particularly tachycardia. Primary endpoint: to compare the proportion of women who did not deliver and did not receive an alternative tocolytic therapy after 7 days of treatment. Secondary endpoints: proportion of women who did not deliver after 2 days of treatment and did not require an alternative tocolytic. Other parameter measured: frequency of uterine contractions, gestational age at delivery, birthweight, maternal and fetal deaths and early drug discontinuation with/without alternative tocolytic treatment.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Women were computer‐randomized into two groups." 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 study.
Blinding of outcome assessment (detection bias) All outcomes	High risk	There was no blinding of outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All women were included in the intention‐to‐treat analysis.
Selective reporting (reporting bias)	Low risk	All outcomes were reported as expected.
Other bias	Low risk	None apparent.