Caesarean section for premature pregnancy

As is known, the problem of "birth trauma" is currently given great importance in medicine. Therefore, despite extensive knowledge in this area, the individual risk of spontaneous birth in premature pregnancy is often underestimated only because it is quite difficult and unusual to consider this complex process based on the category of "trauma".

Thanks to modern methods used in obstetric practice (echography, computer tomography), it has been shown that even in the antenatal period, before the onset of labor, brain hemorrhages are possible. At the same time, it was possible to obtain scientific evidence of the origin of intracranial hemorrhages as a result of the direct impact of labor contractions on the fetus's skull during labor. Thus, the effect of intrauterine pressure on the fetus's head in the second period of labor can reach 15 kg.

Some foreign authors believe that pathophysiologically and neurosurgically, birth does not occur without hidden craniocerebral trauma, i.e. without multiple changes under pressure in the cerebral and facial skull, the base of the skull and the craniocervical junction in the axial organ of the spinal column with accompanying disturbances of macro- and microcirculation. The embryonic brain from the moment of its appearance has fully developed differentiated neurons and in no case represents a shapeless homogeneous mass. Therefore, irreversible circulatory disorders can form in the entire craniocerebral region with extensive subdural and intraventricular hematomas and intraocular hemorrhages.

At the same time, the ensuing microcirculatory acidosis turns into life-threatening cerebral edema. The enormous load on the fetus during childbirth may manifest itself as a disease only many years later.

Depending on the length of service and experience of the doctor, the frequency of cesarean sections in full-term pregnancies varies significantly. When considering the issue of expanding the indications for cesarean sections in premature pregnancies, it is important to take into account the mortality rate of women in labor and women in childbirth in premature births, which, according to research, amounted to 26.8% of the total number of pregnant women, women in labor and women in childbirth who died in the country. The leading causes of death were late toxicosis (26.8%), extragenital diseases (23.4%), bleeding (21.9%), and sepsis (12.4%).

41.4% of women with late toxicosis were delivered by caesarean section; in case of extragenital pathology, 13.4% were delivered by caesarean section. It should be noted that the overwhelming majority of women (61.8%) were delivered by caesarean section. At the same time, the analysis of lethal outcomes in premature births showed that 93.4% of women died after childbirth. Thus, caesarean section in premature pregnancy, as well as in term births, remains a high-risk intervention in terms of maternal mortality and morbidity.

The results of scientific analysis of perinatal mortality show that its main causes are fetoplacental insufficiency in a number of pregnancy complications and extragenital diseases (especially diabetes mellitus), birth trauma and a combination of birth trauma with respiratory failure and pulmonary atelectasis, as well as fetal malformations. Knowledge of these main causes of perinatal mortality allows us to outline reasonable ways to reduce them in both the ante-, intranatal and postnatal periods. In particular, attempts are being made to study the effect of the active phase of labor and the method of delivery on the frequency of intracranial hemorrhages. A number of studies have shown that the overall frequency of hemorrhages that developed in the first 7 days of life was approximately the same as those delivered by cesarean section in the early and late stages of labor, but the time of their occurrence was different. In most children delivered by cesarean section before the active phase of labor, hemorrhages developed within 1 hour of life. In children delivered during the active phase of labor, hemorrhage progressed to grade III-IV regardless of the method of delivery.

Earlier studies discussed the issue of performing a cesarean section in breech presentation during premature birth and in the presence of twins with fetuses weighing less than 2500 g, if one of them is in a breech presentation. For example, if a cesarean section in breech presentation and a pregnancy period of 32-36 weeks was performed with a fetus weighing 1501-2500 g, the number of newborns who died after the operation was 16 times less than in premature births through the natural birth canal. It is important to note that the condition of newborns born by cesarean section was significantly better.

In this case, severe and moderate asphyxia was 2.5 times less in the group of children delivered by caesarean section. Therefore, it is recommended to use this operation more widely in premature births. Other authors, despite the increase in the frequency of caesarean sections in breech presentation and premature births, did not find any differences in the condition of children weighing from 1501 to 2500 g compared to children born through the natural birth canal. Therefore, a number of obstetricians believe that perinatal mortality should be reduced by preventing premature births and continuous monitoring of the fetus.

According to modern data, the frequency of cesarean section in premature pregnancy is about 12%. In almost half of the cases, it is performed on a planned basis, in every fifth woman - due to bleeding and breech presentation of the fetus or its hypotrophy. In half of the women, the operation is performed during labor. Most authors are currently inclined to consider very low body weight (less than 1500 g) during cesarean section deserving further study. The outcomes of cesarean section before 32 weeks of pregnancy deserve attention. In this case, the main indications for surgery are: acute fetal distress, chronic hypoxia, premature birth itself, multiple pregnancy and inevitable premature birth, maternal diseases, combined indications. About 70 % of children delivered before 32 weeks of pregnancy had normal psychomotor development when observed for up to 5 years. The advantages of operative abdominal delivery in case of premature birth with breech presentation of the fetus are convincingly demonstrated. Some authors believe that the outcome of the operation for the newborn is affected by the incision on the uterus, since at gestation periods of 26-32 weeks and fetal weight from 501 to 1500 g, extremely careful delivery is necessary. At the same time, at these periods, poor development of the lower segment of the uterus is observed, and the circumference of the head at 28 weeks is 25 cm and about 30 cm at 32 weeks of pregnancy, the length of the fetus is 23 cm at 26 weeks and 28 cm at 32 weeks of pregnancy, respectively.

At the same time, some authors believe that premature infants delivered by cesarean section have a number of peculiarities during the neonatal period. The outcome of the operation for the fetus is determined by pregnancy complications, the presence and condition of the uterine scar, extragenital diseases of the mother, and the degree of maturity of the fetus. It is believed that in modern conditions, cesarean section for premature pregnancy, and especially in the presence of a uterine scar, should be performed only according to strict indications from the mother.

Despite the fact that many authors refrain from cesarean section in breech presentation and fetal weight less than 1500 g, it should still be noted that the frequency of postnatal death of children is 2 times lower in cesarean section, and the frequency of low Apgar scores and intracranial hemorrhages does not differ in both groups. The highest frequency of the operation was at a pregnancy term of 29-34 weeks. At the same time, it was noted that doctors do not have the opportunity to learn how to deliver babies in breech presentation, since there are two breech births per year for each student. Therefore, the frequency of cesarean section in breech presentation may increase in the future and reach 100%. Currently, all births in breech presentation should end in cesarean section. However, no significant relationship was noted between perinatal mortality rates and the frequency of cesarean sections. Therefore, even today, the question remains acute: does a caesarean section reduce the risk of delivery in premature births with a fetus in breech presentation?

Thus, the use of cesarean section does not reduce the incidence of hypoxia, birth trauma, encephalopathy or neonatal mortality. Therefore, it is concluded that in premature births with a fetus in breech presentation, the use of cesarean section at 29-36 weeks has no advantages over vaginal delivery. Surgery before 29 weeks may be justified in most cases. It has also been established that fetal malformations and fetal respiratory distress are more often observed in breech presentation.

The issue of morbidity and mortality among premature infants born in breech presentation with a birth weight of 1500 g or less, depending on the method of delivery (vaginal or abdominal delivery), deserves great attention. A few studies based on a small number of observations conclude that the effect of the delivery method on infant mortality has not been identified. The causes of infant mortality in both groups were intracranial hemorrhage and extreme immaturity. Objective research methods (pH value in umbilical cord blood, assessment according to the Apgar scale, etc.) show that newborns extracted surgically had better adaptation parameters compared to children delivered vaginally. These studies indicate a favorable effect of timely and gentle delivery by cesarean section on the morbidity of low-birth-weight infants born in breech presentation. In particular, cesarean section can reduce perinatal mortality in breech presentation and low birth weight infants by 50%. In addition, children delivered by cesarean section had lower morbidity compared to those delivered vaginally. Therefore, conclusions are even made about expanding the indications for abdominal delivery in children with low birth weight.

Issues related to pregnancy and childbirth management in multiple pregnancies deserve much attention. A number of modern studies question whether increasing the frequency of cesarean sections would improve the living conditions of children at birth. It is necessary to emphasize the fact that after 35 weeks of pregnancy, the neonatal outcome for the second fetus does not depend on the method of delivery. Other authors believe that if the second fetus is not in the cephalic presentation, then a cesarean section must be performed, even if the first fetus was born through the natural birth canal. A number of researchers believe that with a child's weight over 1500 g, childbirth through the natural birth canal is as safe as with a cesarean section. At the same time, some authors believe that fetal extraction by the pelvic end of the second fetus weighing over 1500 g is the most appropriate alternative to a cesarean section and external version. Therefore, the optimal choice of the method of delivery of the second fetus of twins remains a controversial issue in modern obstetrics. External version of the second fetus in breech presentation of twins is a relatively new achievement in the management of multiple pregnancies. However, a number of studies have shown that external version is associated with a higher failure rate than extraction of the fetus by the breech end. However, no differences in neonatal mortality were found between these methods of delivery. Thus, extraction of the fetus by the breech end of the second fetus of twins weighing over 1500 g is an alternative to cesarean section or external version. However, there are few comparative studies on this issue. This is probably due to the insufficient number of studies on fetal development in twin pregnancies. Fetal development in twin pregnancies is influenced by such parameters as the state of the chorion and the presence of interfetal anastomoses in the placenta in the case of monozygotic twins. It is noted that in twin pregnancies, fetal growth retardation begins at 32-34 weeks. Thus, the body weight of newborn twins is 10% less than the weight of the fetus in a singleton pregnancy. A decrease in growth rates can affect both twins or one of them, and this difference can be 25%. Slowing down of fetal development affects primarily the length and weight of the baby. When studying the status of newborns delivered by cesarean section, it is necessary to take into account the effect of anesthesia and the duration of the interval: uterine incision - delivery on the condition of the newborns. Moreover, if the duration of this interval was less than 90 s, acidosis was more pronounced under epidural analgesia. With an increase in this interval under general anesthesia, an increase in acidosis was also noted. To reduce the trauma of newborns, especially those with low weight,Currently, in the technique of cesarean section, great importance is attached to the vertical incision of the uterus in the area of its lower segment, especially in the transverse position, placenta previa, during hysterectomy and the presence of uterine myoma in its lower segment. This issue remains especially relevant when extracting a fetus weighing 1000-1500 g (isthmic-corporal with a longitudinal incision of the uterus).

It is important to recognize that the increase in the frequency of cesarean sections in preterm pregnancies is increasingly based on neonatological indicators - immaturity, perinatal infection, risk of birth trauma for the mother, fetus and newborn. Therefore, there are voices in defense of the position that cesarean sections should not be performed earlier than 32 weeks of pregnancy.

In the prognostic assessment of premature fetuses and fetuses with hypotrophy (severe fetal growth retardation): in case of fetal growth retardation, the survival rate of children after cesarean section is currently almost 40%, and in case of prematurity - 75%. The main causes of death were placenta previa (30%), fetal malformations, polyhydramnios, Rhesus incompatibility. In general, the risk of mortality for fetuses weighing less than 1500 g is significantly higher in case of vaginal delivery than in case of cesarean section. The prognosis for a fetus at a gestation period of less than 28 weeks is usually questionable, at a gestation period of 28-32 weeks - more favorable. It is important to emphasize that the risk of developing respiratory distress syndrome in newborns is proportional to the gestational age and is possibly higher in newborns delivered by cesarean section than in those delivered vaginally.

There are indications in the literature of an increased risk of respiratory distress syndrome depending on the indications for cesarean section, including antepartum hemorrhage, diabetes mellitus, abnormal cardiotocogram in the fetus, and toxicosis of pregnancy. Respiratory distress syndrome increases as the infant's weight decreases: at 1000-1499 g - 25%; 1500-1999 g - 14%; 2000-2499 g - 7.1%.

Thus, the need for surgical delivery in premature pregnancy arises in almost 75% of cases before the onset of labor.

The main indications for caesarean section from the fetal side are:

• fetal hypoxia, caused mainly by fetoplacental insufficiency due to late toxicosis, especially in combination with diabetes mellitus;
• breech presentation of the fetus when symptoms of disruption of vital functions appear.

Almost 50% of cesarean sections for premature pregnancies are performed when labor has begun. The most common indications for it are:

• transverse and oblique position of the fetus;
• deterioration of the fetus's condition against the background of extragenital pathology (mainly diabetes mellitus) in women in labor;
• threatening rupture of the uterus along the scar;
• ineffectiveness of labor induction when amniotic fluid has broken.

In conclusion, it should be noted that perinatal mortality in women with premature pregnancy by caesarean section is only 1.3 times higher than perinatal mortality in vaginal birth (in full-term pregnancy, perinatal mortality is 3-6 times higher in caesarean section than in vaginal delivery).

The highest perinatal losses are observed among newborns weighing 1500 g or less, both in operative delivery and in vaginal delivery, with perinatal mortality rates in both cases being virtually identical and exceeding 75% in all years of observation. This means that in the absence of a developed, highly qualified neonatological service, a child weighing 1500 g or less is a relative contraindication to abdominal delivery in the interests of the fetus; cesarean section in such conditions should be performed primarily for vital indications on the part of the mother.

Thus, women with premature births should be classified as a high-risk group. They have a relatively frequent history of miscarriage, artificial termination of pregnancy, abnormal development of the genitals, and extragenital diseases. Therefore, the frequency of premature births is higher in the group of women with various obstetric complications. Childbirth should be performed in a specialized obstetric hospital, where there are opportunities to prevent possible complications for the mother and fetus.

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