Stock 1993.

Methods	RCT.
Participants	Inclusion criteria: breech presentation between 36 and 42 weeks with no contraindication to ECV. N = 63. Exclusion criteria: diabetes, heart disease, thyrotoxicosis, ruptured membranes, multiple pregnancy, uterine scar, placenta praevia, oligohydramnios, impaired fetal growth, nuchal cord, placenta praevia.
Interventions	Intervention 1:tocolytic: ritodrine ‐ beta stimulant (A1) ‐ parenteral. Group B: ritodrine 0.3 mg per minute infusion for 30 minutes and during the procedure, and placebo bolus injection. N = 21. Intervention 2:tocolytic: hexoprenaline ‐ beta stimulant (A1) ‐ parenteral. Group C: placebo infusion and hexoprenaline 10 micrograms bolus injection. N = 21. Comparison:placebo. Group A: placebo infusion and bolus injection. N = 21. For the purposes of this review, which addresses the effectiveness of IV tocolysis for ECV rather than the evaluation of specific tocolytic agents, intervention 1 (group B) and intervention 2 (group C) have been combined. Nulliparous = 18 in tocolytic groups and 9 in placebo group. Multiparous = 24 in tocolytic groups and 12 in placebo group. We have not set up a subgroup comparison of 1 beta stimulant vs another, so the data from this study on failed ECV for ritodrine (7/21) vs hexoprenaline (5/21) are not included as a direct comparison.
Outcomes	Immediate ECV success; ECV completed < 1 minute; fetal bradycardia during ECV.
Notes	Improved ECV success rate with tocolysis reached statistical significance for hexoprenaline but not for ritodrine. Study authors decided not to continue the ritodrine/placebo arm of the trial to completion.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	'Each investigator had a separate randomisation sequence. These were in sets of 3 to the 3 groups, stratified for parity.' Method of randomisation not specified.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Placebo‐controlled trial. Practitioners were blind to group allocation, as were the women.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Practitioners were blind to group allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No evidence of exclusions of loss to follow‐up.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	High risk	No statistically significant differences between groups in terms of parity, height, age or gestation at time of ECV (see Table 2 on page 266). No differences between groups regarding fetal biparietal diameter, abdominal circumference. Femur length or AFI. Women in ritodrine group were significantly lighter than those in the other 2 groups. Trial stopped early for benefit.