Study designs of evaluations included in the review
Retrospective and prospective cohort studies and randomised controlled trials (RCTs) were eligible for inclusion in the review.
Specific interventions included in the review
Studies that compared planned Caesarean section with planned vaginal birth were eligible for inclusion in the review. Planned Caesarean sections included those performed before labour or shortly after labour begun, as well as those performed for reasons other than twins, such as placenta previa and hypertension. Planned vaginal births included all births occurring after a trial of labour, irrespective of whether they were delivered vaginally or by emergency Caesarean.
Participants included in the review
Studies were included if they considered twin pregnancies that had reached at least 32 weeks' gestation, or if both babies weighed at least 1,500g. The studies examined breech first twins (1 study), twins of all presentations (1 study), vertex/nonvertex twins weighing at least 1,500g (1 study) and vertex/nonvertex twins with an estimated gestational age of 35 to 42 weeks (1 study).
Outcomes assessed in the review
The inclusion criteria for the outcomes do not appear to have been pre-specified. The included outcomes were perinatal or neonatal mortality, low 5-minute Apgar score, neonatal morbidity and maternal morbidity.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.