**4.1 Vaginal delivery-ceasarean section**

In general, both in single pregnancies and in twin pregnancies, the best way to complete delivery is vaginal delivery due to:


No adverse effects of vaginal delivery were observed with regard to morbidity and mortality of the latter even when its projection is not head-on. After the birth of the first baby, the presentation of the second is often changed, as a result the second twin may have a vertical shape, an abnormal presentation and therefore a caesarean section is preferred. The second twin in case of change of presentation has an increased risk of perinatal asphyxia and therefore the organization of an emergency caesarean section is extremely necessary. Important factors for how to complete the birth of twins are:

Presentation of the first twin

Estimated birth weight

In the majority of cases 75–85% the fetus iswith head presentation and if there are no risk factors in diamniotic twins' vaginal deliveryis indicated. The big problem is in the second twin, especially when it is not in head presentation, there are contradictory data from the literature, while some authors report that there are no advantages of caesarean section over vaginal delivery, other authors emphasize the risks of vaginal delivery such as increased perinatal morbidity, mortality and fetal distress.

Disadvantages of cesarean sections are increased maternal morbidity and increased cost of health benefits. In newborns weighing less than 600 gr, or in 26 weeks of gestation, vaginal delivery is recommended due to low survival rates [48–58].

#### *Twin Pregnancies Labour Modus and Timing DOI: http://dx.doi.org/10.5772/intechopen.95982*

Between 600 and 2000 g weight, or in 27–8 weeks of gestation, if the first fetus is not in head presentation, then a caesarean section is recommended to avoid umbilical cord prolapse and twin interlocking.

If the first fetus is in head presentation should made an effort for vaginal delivery. If the se fetus is not in head presentation at internal cephalic version should attempt immediately and in failure organization of an emergency cesarean section. In cases where the second twin is not in head presentation but has a weight of over 2000 g external cephalic version should attempt and in case of failure internal cephalic version should attempt under local anesthesia and in repeated failure emergency cesarean section should be done. In cases of weight difference from 500 g of the weights of the two fetuses cesarean section in monoamniotic twins should be performed. Cesarean section is a routine method for termination of labor to prevent umbilical cord prolapse and twin interlocking in IUGR, conjoined twins or twins with TTTS [55–58].

### **4.2 Main complications of vaginal twin delivery**

Inter-anchoring of twins in a longitudinal lie can occur in either cephalic presentations or in breech presentations.

Acute twin-to-twin transfusion syndrome is rare and is associated with changes in intravascular pressure along large vascular anastomoses and intrauterine pressure during labor, creating a risk of heart failure and exchange transfusion between twins.

It is recommended in low-risk twin pregnancies of dichorionic twins a birth planning for 37th week and of monochorionic twins for 36th week.

In monochorionic monoamniotic pregnancies, caesarean section is preferred to avoid overlapping (1/1000 births). According to the Bibliography the number of cesarean sections required to prevent a neonatal death is between 264 and 1451.

The above reports are disadvantageous in terms of their validity because the data on how to arrange the birth of the 2nd fetus, the interval between the 1st and 2nd births as well as the type of obstetric manipulations are missing or insufficient. Therefore, the potential benefits to the newborn of a Caesarean section should be weighed against the potential short-term and long-term risks of complications from the mother.

According to recent data on short-term and long-term maternal morbidity, scheduled Caesarean section is not recommended in all low-risk twin pregnancies. In contrast, scheduling vaginal delivery in twin pregnancies >35 weeks with a head projection of the 1st fetus is a relatively safe and acceptable method, provided that staff are experienced in arranging the 2nd fetal delivery.

The way of terminating the labor in twin pregnancies is increasingly troubling the modern obstetrician due to the large number of twin pregnancies that result from the application of assisted reproduction methods. The frequency of stillbirths and perinatal morbidity and mortality are higher in twin pregnancies.

Retrospective studies have shown that caesarean section has the advantage of reducing the morbidity of the 2nd fetus [55–58].

Many meta-analyzes of studies comparing selective Cesarean section with vaginal delivery do not find an advantage in performing cesarean section. Due to the small number of the above studies, more and larger ones need to be carried out. Future research should also look at the possible causes of increased stillbirths in twin pregnancies as well as investigating the role of chorionicity in the normal or non-development of childbirth [55–58].

Due to the dramatic increase in the frequency of Caesarean sections observed in recent years and the increase in the frequency of twin pregnancies, and despite the

higher risk of perinatal asphyxia compared to single pregnancies, it is suggested by many studies near the probable date of delivery. According to most recent literature, it is recommended between 37 + 3 and 37 + 5 weeks of pregnancy [55–58].

Nowadays, there is an increase in the frequency of twin pregnancies after spontaneous conception in developed countries, which is explained by the choice to have children at an advanced age (approximately 6% compared to 2.3% 4 years ago). In addition, over the last decade there has been an increase in the incidence of twin pregnancies worldwide as a result of the increasing demand for assisted reproduction methods. Especially in Canada this increase amounted to 15% during 2007–2012.

Twin pregnancies are characterized by increased perinatal morbidity and mortality require larger amounts of surfactant after admission to the Neonatal Intensive Care Unit department especially in the early week and are accompanied by increased maternal morbidity and mortality attributed mainly to the increased risk of bleeding [44–58].

#### **4.3 Increased mortality of full-term twins**

According to bibliographic sources in twin pregnancies there is an increase in the relative risk of stillbirth and the risk of unpleasant events during childbirth is increased.

The neonatal mortality of twins compared to single pregnancies is 4.3‰ against 3.8‰ for newborns weighing 2501-3000gr, and 7.4‰ against 2.2‰ for newborns weighing 3000gr. Double mortality during childbirth is also reported.

Due to the evolution of perinatal neonatal care, there is a decrease in the risk of perinatal death of twins during the last three decades. Higher perinatal mortality was also observed in twin neonates with birth weight > 2500gr compared to corresponding weights of single pregnant neonates.

Referring to retrospective studies involving large numbers of twin births, selective caesarean section can also reduce perinatal mortality of full-term twins by 75%. Also important factors that influence the obstetrician to the choice of elective caesarean section are the often observed relatively high (> 35 years) age of the interest rates, as well as the fact that the majority are first-borns. In cases of premature births or severe retardation of intrauterine growth, most recommend caesarean section in pregnancies <32 weeks or when the weight of the fetus is <1500gr.

Regarding the method of conception, twin pregnancies after IVF, ICSI show a higher frequency of premature births, births of infants with residual weight as well as other events. The risk of stillbirth increases after the completion of the 37th week of pregnancy and is 6–9 times higher in dichorionic twins and even more in monochorionic. It is recommended to perform selective Caesarian section in the dichorionic twins in the 37th week and the 36th in the monochorionic twins [44–58].

#### **4.4 Delivery termination time**

The International Society for Twin Studies and SOGC recommend giving birth before the 38th week of pregnancy. It is considered a reasonable choice to design a selective low transverse cesarean section during the 38th week.

#### *4.4.1 Absolute indications*

Monoamniotic twins due to high risk of umbilical cord prolapse. Siamese twins

#### *Twin Pregnancies Labour Modus and Timing DOI: http://dx.doi.org/10.5772/intechopen.95982*

When the presentation of the 1st is not cephalic.

When the 1st of the embryos is in breech presentation, it is recommended to perform a Caesarean section due to the insertion and impossibility of descent of the protruding parts through the pelvic tube, especially when the 2nd embryo is in cephalic presentation. Although the above development is very rare, it is accompanied by high perinatal mortality.

Even when the projection is head-shaped, vaginal delivery remains a controversial choice, due to the increased likelihood of obstetric complications, which usually occur after the birth of the first fetus (placental obstruction, umbilical cord prolapse, fetal bradycardia). Moreover, we should note that the maternal postoperative infections are more frequent, as it becomes necessary to perform an emergency cesarean section for the second fetus.

Empirically and traditionally, the attempt for vaginal delivery is made when the projection of the first fetus is head and there are no other complications, but this has not been proven by well-designed prospective studies. According to the same study, the main cause of neonatal death in relation to the projection of the birth of the second fetus is suffocation-acidosis of the fetus, while the above cause can also cause cerebral palsy.

Remarkably, in most of the younger Obstetricians there is a lack of sufficient capacity, training and experience to deal with success with the increased obstetric requirements of the second fetus, especially when the projection is not cephalic.

According to studies that openly state the choice of whether or not to perform a caesarean section when the projection of the 2nd was not cephalic, 84% of caesarean sections were confirmed with similar rates of neonatal morbidity and mortality between the 2 fetuses. The manner of termination of childbirth in twin pregnancies is increasingly problematic for the modern obstetrician due to the large number of twin pregnancies resulting from the application of assisted reproduction methods. The frequency of stillbirths and perinatal morbidity and mortality are higher in twin pregnancies.

Several studies have shown that vaginal delivery of the 2nd fetus is accompanied by increased perinatal morbidity and mortality and they consider it necessary to perform a selective Cesarean section. In all twin pregnancies, the 2nd fetus can be significantly protected.

Based on the above, it is proposed the vaginal arrangement of the birth of twins only in cases of interest rates: multipara women, aged <35 years, with cephalic presentation of both fetuses, in full-term, without pathology pregnancies, the duration of which does not exceed 38 weeks and which occurred after normal conception. In all other cases, the execution of Caesarian section is proposed [44–58].
