**2. Risk of fetal death in the third trimester for twin pregnancies**

Multiple pregnancies have high rates of mortality and morbidity when compared to single pregnancies. This is mainly due to prematurity, complications close to delivery, and placental insufficiency [1].

Just like DC gestations, there are no high-quality studies to respond with great certainty the right time for terminate monochorionic pregnancies. Most specialists in large reference centers recommend delivery of monochorionic/diamniotic twins between 36 + 0 and 36 + 6 weeks. This may be the point of balance between the already reduced risk of prematurity and the risk

Time and Mode of Delivery in Twin Pregnancies http://dx.doi.org/10.5772/intechopen.80092 213

There is still a lot of divergence between medical societies for the correct time of delivery. ACOG suggests delivery of monochorionic twins between 34 + 0 to 37 + 6 weeks of gestation [7] and the North American Fetal Therapy Network suggests delivery at 36 + 0 to 37 + 6 weeks of gestation [9]. However, others delegate delivery at 32 weeks of gestation [10]. It is clear that in cases of Twin-Twin Transfusion Syndrome, most of deliveries are performed earlier and

On the other hand, in monoamniotic pregnancies, most specialized centers in the world recommend delivery between 32 and 34 weeks. This fact is justified by the high rate of perinatal mortality in the third trimester (30–70%) and has as main motive the umbilical cords entangle-

The mode of delivery in twin pregnancy depends on multiple factors and is very controversial in the literature. The most important factors to be considered on deciding the delivery mode are the fetus presentation, especially the first twin, fetal weight, weight difference between the fetuses, gestational weight and maternal clinical conditions. Women's parity is also a condition with high influence in mode of delivery in a twin pregnancy, as nulliparous usually

The decision on either performing an elective cesarean delivery must consider the best neonatal and maternal outcomes, to reduce neonatal morbidity and mortality, maternal complications and preserving the women's reproductive future. The biggest risk in a vaginal delivery is for the second twin, as complications can occur after the delivery of the first twin, including

It is important to consider that conditions that would indicate a cesarean section in singleton

Determining fetal presentation is fundamental in the decision of the mode of delivery. The presentation of twin pairs in a term twin pregnancy is 40% of the times cephalic/cephalic, 35–40% cephalic/non-cephalic and only 20% with the first twin non-cephalic [15]. It is a general consensus that, when both fetuses are in cephalic presentation, a vaginal delivery should be attempted [13–15]. However, it is important to notice that the second twin change its pre-

this depends on the degree of complication that is present.

**5. Delivery mode: vaginal delivery vs. cesarean section**

result in less success when attempting a vaginal delivery [13].

placental abruption, cord prolapse and long delivery intervals [14].

pregnancies should also be applied in multiple pregnancies.

sentation in about 20% of the time, after the first one is born [15].

**5.1. Fetus presentation**

ment in the same amniotic chamber [4, 11, 12].

of fetal death [9].

In fact, this risk is related to chorionicity. The monochorionic (MC) pregnancies present a higher incidence of perinatal mortality, higher admission in neonatal intensive care unit and low birth weight [3]. It is possible that the single placental mass shared between pairs originates from an imbalance in placental anastomoses, may be overloaded in the third trimester [4].

A large Dutch cohort with 1407 multiple pregnancies showed that after 32 weeks' gestation, mortality was 11.6% in MC and 5% in dichorionic (DC) [5]. The risk of uterine death was significantly higher in MC than in DC (hazard ratio 8.8, 95% CI 2.7–28.9), and in most cases no change in fetal status was observed. The authors concluded that fetal vitality control was not sufficient to prevent adverse events and delivery should be planned up to the 37th week for MC.

A study with 94,170 multiple deliveries showed that the risk of fetal death increased significantly between 37 and 38 weeks of gestation in twin pregnancies. This risk was higher between 34 and 37 weeks of gestation in triplet pregnancies. The risk of child death after delivery gradually declined as pregnancies neared full term. This group recommended increased fetal surveillance after 34 weeks of gestation in multiple pregnancies [6].
