**13. Time and mode of delivery in monochorionic pregnancies**

There are many suitable recommendations for twin gestation term in the literature. It is known that the risk of fetal death becomes gradually increased from 38 weeks of pregnancy and it is greater in case of monochorionic pairs [122]. Thus, in many universities' protocols, resolution is recommended for dichorionic pregnancies around 38 weeks, at 37 weeks for monochorionic (devoid of complications) and at 32 to 34 weeks in cases of single amniotic chamber [123].

The main risk associated with vaginal delivery is connected to the possibility of anoxia of the second twin. Thus, studies have shown that elective cesarean delivery at term pregnancy can reduce to 75% the risk of perinatal death [124]. However, a Cochrane systematic review showed that cesarean delivery performed by non-cephalic presentation of the second twin is associated with increased maternal morbidity without improved neonatal outcome [125].

The most important factors in the decision of the delivery mode include the presentation of the fetus, gestational age, and weight or the weight difference between the fetuses. In term births, if only the first twin is in cephalic presentation without detected adversities, vaginal delivery may proceed. If the first twin is neither cephalic, nor presents weight difference for the second fetus, being equal or less than to 500g, caesarean section seems to be a good indication. In preterm pregnancies without other complications or fetal weight lower than 1.500g, a cesarean remains as the best option [126].

Results from the biggest randomized trial conducted by the Twin Birth Study Collaborative Group established major key points [127]. Caesarean section is indicated for all monoamniotic twins, conjoined twins, non-vertex first twin and other classic indications similar to singleton pregnancies. During labour and delivery of a twin pregnancy, neuroaxial anesthesia is preferable. Whenever there is a non-vertex second twin, vaginal delivery is indicated as long as the estimated weight is between 1500-4000g and the obstetrician feels comfortable and skilled [127, 128].
