The incidence of twins varies considerably between communities and families and has recently increased because of the number of older mothers and the use of fertility treatments and assisted conception. Infants from a twin pregnancy are at a higher risk of death around the time of birth than are infants from a singleton pregnancy. Some of this is due to a higher risk of preterm birth. The second-born twin has an increased risk of a poor perinatal outcome compared with the first-born twin.
A policy of planned vaginal birth for women with a twin pregnancy in a hospital setting is associated with a 30% to 40% rate of emergency caesarian section. Among those twins in which the first twin is born vaginally, there is still a risk of emergency section for the birth of the second twin. It is possible that some of the adverse outcomes may be avoided by appropriately timed delivery by caesarean section but the risks of caesarean section for the mother in the current and subsequent pregnancies must be taken into account.
In this review we identified only one small trial with unconfirmed allocation concealment that randomly assigned the women to planned caesarean section or planned vaginal birth. The 60 women were in labour at 35 or more weeks' gestation with the leading twin cephalic and the second twin non-cephalic. The perinatal outcome was similar between the two groups and the trial was too small to exclude the possibility of clinically meaningful benefits of either approach. 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.