Abstract: We included two trials comparing planned caesarean section versus planned vaginal birth for twin pregnancies. Most of the data included in the review were from a multicentre trial where 2804 women were randomised in 106 centres in 25 countries. All centres had facilities to perform emergency caesarean section and had anaesthetic, obstetrical, and nursing staff available in the hospital at the time of planned vaginal delivery. In the second trial carried out in Israel, 60 women were randomised. We judged the risk of bias to be low for all categories except performance (high) and outcome assessment bias (unclear). There was no clear evidence of differences between women randomised to planned caesarean section or planned vaginal birth for maternal death or serious morbidity (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.67 to 1.11; 2844 women; two studies; moderate quality evidence). There was no significant difference between groups for perinatal or neonatal death or serious neonatal morbidity (RR 1.15, 95% CI 0.80 to 1.67; data for 5565 babies, one study, moderate quality evidence). No studies reported childhood disability. For secondary outcomes there was no clear evidence of differences between groups for perinatal or neonatal mortality (RR 1.41, 95% CI 0.76 to 2.62; 5685 babies; two studies, moderate quality evidence), serious neonatal morbidity (RR 1.03, 95% CI 0.65 to 1.64; 5644 babies; two studies, moderate quality evidence) or any of the other neonatal outcomes reported. The number of women undergoing caesarean section was reported in both trials. Most women in the planned caesarean group had treatment as planned (90.9% underwent caesarean section), whereas in the planned vaginal birth group 42.9% had caesarean section for at least one twin. For maternal mortality; no events were reported in one trial and two deaths (one in each group) in the other. There were no significant differences between groups for serious maternal morbidity overall (RR 0.86, 95% CI 0.67 to 1.11; 2844 women; two studies) or for different types of short-term morbidity. There were no significant differences between groups for failure to breastfeed (RR 1.14, 95% CI 0.95 to 1.38; 2570 women, one study; moderate quality evidence) or the number of women with scores greater than 12 on the Edinbugh postnatal depression scale (RR 0.95, 95% CI 0.78 to 1.14; 2570 women, one study; moderate quality evidence). Data mainly from one large, multicentre study found no clear evidence of benefit from planned caesarean section for term twin pregnancies with leading cephalic presentation. Data on long-term infant outcomes are awaited. Women should be informed of possible risks and benefits of labour and vaginal birth pertinent to their specific clinical presentation and the current and long-term effects of caesarean section for both mother and babies. There is insufficient evidence to support the routine use of planned caesarean section for term twin pregnancy with leading cephalic presentation, except in the context of further randomised trials.

Plain-language summary: In this review we included two randomised trials comparing planned caesarean versus planned vaginal birth for twin pregnancies which together included 2864 women. For important outcomes the evidence was assessed as being of moderate quality. For maternal mortality no events were reported in one trial and two deaths (one in each group) in the other. There was no clear evidence of differences between women randomised to planned caesarean or planned vaginal birth for death or serous illness in either the mothers or babies. No studies reported childhood disability. The number of women undergoing caesarean section was reported in both trials. Most women in the planned caesarean group had treatment as planned (90.9%), whereas in the planned vaginal birth group 42.9% had caesarean section for at least one twin. There were no significant differences between groups for failure to breastfeed or for postnatal depression. There is very little clear research evidence to provide guidance on the method of birth for twin pregnancies. The benefits and risks should be made available to women, including short-term and long-term consequences for both mother and babies. Future research should aim to provide more clarity on this issue as medical interventions in the birth process should be avoided unless there is reasonable clinical certainty that they will be of long-term benefit.