Bomfim‐Hyppólito 1998.

Methods	Quasi‐randomised controlled trial. Women were divided into sitting versus lying positions during labour according to their height. If their height ended in an even figure, they were assigned to the sitting position, if in an odd number to the lying position.
Participants	248 women who delivered at the Maternidade Escola Assis Chateaubriand of the Ceara Federal University. Included women with a singleton pregnancy at term with a vertex presentation. It excluded women who showed a preference for the other birthing position or who changed their minds during labour, those whose babies were less than 2500 g or heavier than 4000 g in weight and if the birth was any other than spontaneous vaginal. Also excluded seven patients who needed an episiotomy.
Interventions	127 participants randomised to vertical (sitting) position during birth defined as an inclination of the back support of the birth table at 60º with support for the feet and legs bent at 90°. 121 participants randomised to horizontal (lying) position during birth on an ordinary birthing table.
Outcomes	Blood loss and changes in haemoglobin and haematocrit measured before birth, during labour and 24 hours after labour. Duration of expulsion period according to the presence of cord around the neck and fetal position. Incidence of vulvo‐perineal lacerations. Apgar scores at 1 and 5 minutes.
Notes	Women who delivered in the vertical position were slightly but significantly younger than those who delivered in the horizontal position.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Dependent on height. If their height ended in an even figure, they were assigned to the sitting position, if in an odd number to the lying position.
Allocation concealment (selection bias)	High risk	Inadequate ‐ predetermined allocation according to height.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and personnel were aware of allocation.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No incomplete data.
Selective reporting (reporting bias)	Low risk	All outcomes reported.
Other bias	Low risk	No other bias found.