Taavoni 2011.

Methods	Randomised trial.
Participants	62 women, Tehran, Iran. 31 study participants: nulliparous 31 control participants: nulliparous Inclusion Criteria: Parity: nulliparous, Pluralty: singleton, Gestation: 38 ‐ 40 weeks, Onset of labour: spontaneous, Other: cephalic presentation; cervical dilatation between 4 to 8 cm; anticipation of a normal birth; no history of infertility; aged 18 to 25 years.
Interventions	Study group: 29 women were allocated to use a birth ball There were two post randomisation exclusions from the study group. Reasons included: dissatisfied with sitting on the ball during birth ball movements (n = 1); caesarean birth because of lack of descent of the fetal head (n = 1). Control group: 31 women were allocated to usual care. Routine care consists of the parturient lying on the bed without ambulating or any intervention.
Outcomes	Maternal Outcomes: Duration of first stage labour. Mode of birth Maternal pain Neonatal Outcomes: Nil.
Notes	1. Duration of first stage labour reported as duration of active phase. 2. No mode of birth outcomes for vaginal birth or operative vaginal birth were given. If there was a need for analgesic medication, or if obstetric complications occurred, the participant was immediately referred to an obstetrician and other professionals as needed, then excluded from the study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	60 volunteer women (convenience sample) were randomly allocated using a table of random numbers.
Allocation concealment (selection bias)	High risk	If the number was even, women were assigned to the birth ball group, if the number was odd, women were assigned to control group.
Blinding (performance bias and detection bias) Women	High risk	Not feasible.
Blinding (performance bias and detection bias) Clinical staff	High risk	Not feasible.
Blinding (performance bias and detection bias) Outcome assessor	Low risk	The individual responsible for data analysis was masked to the study purposes to minimise any bias that might arise from knowledge about the participants.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	There were two post randomisation exclusions reported: dissatisfied with sitting on the ball during birth ball movements (n = 1); caesarean birth because of lack of descent of the fetal head (n = 1). The total number of participants included for duration of labour and maternal pain data is not clearly stated. It is unclear if the number includes totals before or after exclusions. It is also not clear if the group numbers were even before or after the exclusions.
Selective reporting (reporting bias)	Unclear risk	Unclear.