BACKGROUND For centuries, there has been controversy around whether being upright (sitting, birthing stools, chairs, squatting, kneeling) or lying down have advantages for women delivering their babies. OBJECTIVES To assess the benefits and risks of the use of different positions during the second stage of labour (i.e. from full dilatation of the uterine cervix). SEARCH METHODS We searched the Cochrane Pregnancy and Childbirth Group Trials Register (28 February 2012). SELECTION CRITERIA Randomised or quasi-randomised controlled trials of any upright or lateral position assumed by pregnant women during the second stage of labour compared with supine or lithotomy positions. Secondary comparisons include comparison of different upright positions and the lateral position. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trials for inclusion and assessed trial quality. At least two review authors extracted the data. Data were checked for accuracy. MAIN RESULTS Results should be interpreted with caution as the methodological quality of the 22 included trials (7280 women) was variable.In all women studied (primigravid and multigravid) there was a non-significant reduction in duration of second stage in the upright group (mean difference (MD) -3.71 minutes; 95% confidence interval (CI) -8.78 to 1.37 minutes; 10 trials, 3485 women; random-effects, I² = 94%), a significant reduction in assisted deliveries (risk ratio (RR) 0.78; 95% CI 0.68 to 0.90; 19 trials, 6024 women, I² = 27%), a reduction in episiotomies (average RR 0.79, 95% CI 0.70 to 0.90, 12 trials, 4541 women; random-effects, I² = 7%), an increase in second degree perineal tears (RR 1.35; 95% CI 1.20 to 1.51, 14 trials, 5367 women), increased estimated blood loss greater than 500 ml (RR 1.65; 95% CI 1.32 to 2.60; 13 trials, 5158 women, asymmetric funnel plot indicating publication bias), fewer abnormal fetal heart rate patterns (RR 0.46; 95% CI 0.22 to 0.93; two trials, 617 women). In primigravid women the use of any upright compared with supine positions was associated with: non-significant reduction in duration of second stage of labour (nine trials: mean 3.24 minutes, 95% CI 1.53 to 4.95 minutes) - this reduction was largely due to women allocated to the use of the birth cushion. AUTHORS' CONCLUSIONS The findings of this review suggest several possible benefits for upright posture in women without epidural, but with the possibility of increased risk of blood loss greater than 500 mL. Until such time as the benefits and risks of various delivery positions are estimated with greater certainty, when methodologically stringent data from trials are available, women should be allowed to make choices about the birth positions in which they might wish to assume for birth of their babies.