Eleven studies (n=2,503) were included: five RCTs (n=433), five prospective cohort studies (n=1,139), two of which used historical controls, and one retrospective cohort study (n=762). Two RCTs also included ongoing cohort studies (n=169).
Adverse maternal outcomes: these were rarely reported and it was unclear whether the included studies investigated the event rates in the control group as well as the intervention group. There were two cases of antepartum haemorrhage or vaginal bleeding in 618 women following ECV. There were no cases of uterine rupture, pre-labour rupture of membranes and placental abruption, though these were only investigated in single studies. There was an increase in the number of women with onset of labour within 24 hours compared with the control group (1 study); the RR was 2.38 (95% CI: 0.63, 8.95), though this was not statistically significant.
Adverse foetal outcomes: there was increased risk of a nuchal cord in the ECV group compared with the control (2 studies); the RR was 2.05 (95% CI: 0.87, 4.84), though this was not statistically significant. There were no cases of cord prolapse although this was investigated in only one study. There were no cases of foetal death within 24 hours in the three studies that assessed this outcome in the intervention and control groups. There was no difference between the intervention and control groups in rate of perinatal deaths (3 studies; RR 0.95, 95% CI: 0.13, 6.68). The authors stated that there was no evidence of heterogeneity for any outcome that was pooled (P>0.1).
Side-effects of ECV: the most frequently reported maternal side-effects of ECV were mild or moderate discomfort during the procedure (35% of women; 3 studies). Increased foetal heart rate was reported in 10% of cases (1 study) leading to delivery in 1.1%, and transient foetal bradycardia in 6.7% of cases (8 studies). Other infrequent side-effects were also reported.
ECV success: the overall success rate for ECV was 68% (95% CI: 65, 70) compared with spontaneous version from breech to cephalic presentation of 14% (95% CI: 12, 16) in the control group. ECV was significantly more successful among multiparae (78%) than primiparae women (48%) and in African (89%) compared with non-African women (62%; P<0.001).