Characteristics of physiological delivery

Childbirth is a complex physiological process, during which the contents of the uterus (fetus, amniotic fluid, placenta and membranes) are expelled. The clinical course of this process is characterized by an increase in the frequency, power and duration of uterine contractions, progressive smoothing and opening of the cervix and fetal movement through the birth canal. Some doctors believe that the following criterion is true: if the inner pharynx is still being palpated, then the birth has not yet occurred, the fights, if they are even sufficiently felt, should refer to the fights during pregnancy. The beginning of smoothing of the cervix (from the side of the opening internal pharynx) is the first sign of the onset of labor.

The beginning of labor is considered to be a regular generic activity, when the contractions are repeated every 10-15 minutes, i.e. With the correct periodicity, and without ceasing, lead to childbirth.

The whole cycle of births is divided into 3 periods:

1. Opening period.
2. Period of exile.
3. Birth period afterbirth.

Generic pathways consist mainly of two parts: from a soft pedigree tube and a bone pelvis.

E. Friedman gave a graphic representation of genera (partogram). Most comprehensively, these data are displayed in his monograph "Childbirth: Clinical Evaluation and Management" (1978). In methodical recommendations "Anomalies of labor". It is considered expedient to allocate a latent and active phase in the first stage of childbirth.

The latent phase is the interval (the preparatory period according to Friedman) of time from the beginning of regular contractions to the appearance of structural changes in the cervix of the uterus and the opening of the uterine pharynx by 4 cm). The duration of the latent phase in primiparas is about 6% h, and in the re-birth phase - 5 h. The duration of the latent phase depends on the state of the cervix, parity, pharmacological effects and does not depend on the weight of the fetus.

After the latent phase, the active phase of labor begins, which is characterized by the rapid opening of the uterine throat (from 4 to 10 cm).

In the active phase of childbirth, the following phases are distinguished: the phase of initial acceleration (acceleration), the phase of fast (maximum) ascent and the deceleration phase.

The rise of the curve of the partograph indicates the effectiveness of childbirth: the more steep the rise, the more efficient the delivery. The deceleration phase is explained by the desire of the cervix for the head at the end of the first stage of labor.

The normal speed of moving the fetal head with the opening of the cervix for 8-9 cm for the primiparum is 1 cm / h, for re-birth - 2 cm / h. The speed of lowering the head depends on the efficiency of the expelling forces.

For a dynamic assessment of cervical dilatation in childbirth, it is advisable to use the partogram (a graphic method for assessing the rate of cervical dilatation in labor). The rate of cervical dilatation in the latent phase is 0.35 cm / h, in the active phase - 1.5-2 cm / h in the primipara and 2-2.5 cm / h in the re-parent. The rate of cervical dilatation depends on the contractility of the myometrium, the resistance of the cervix and the combination of these factors. Disclosure of the uterine pharynx from 8 to 10 cm (deceleration phase) is at a lower rate - 1-1.5 cm / h. The lower limit of the normal opening speed of the uterine throat in the active phase in primiparas is 1.2 cm / h, and in the re-birth phase - 1.5 cm / h.

At present, there is a shortening of the length of labor compared to the figures given earlier. This is due to many factors. The average duration of labor in primipara is 11-12 hours, in repetitious - 7-8 hours.

It is necessary to distinguish between rapid and rapid births related to pathological, and according to VA Strukov - to physiological. Rapid are the genera that the primiparas last less than 4 hours, and in the re-borns less than 2 hours. Fast genera are considered to have a total duration of 6 to 4 hours in the primiparous, and in the re-birth, from 4 to 2 hours.

The beginning of labor is considered regular, painful contractions, alternating every 3-5 minutes and leading to structural changes in the cervix. The authors on a large clinical material determined the duration of labor in the first- and second-genus (the total number of cases was 6,991 maternity wards) without and with epidural analgesia. The total length of labor without anesthesia was 8.1 ± 4.3 h (maximum 16.6 h) in primiparas, and in re-births - 5.7 ± 3.4 h (maximum 12.5 h). The second stage of labor was 54 + 39 min (maximum - 132 min) and 19 ± 21 min (maximum - 61.0 min), respectively.

When epidural analgesia was used, the duration of labor was 10.2 ± 4.4 hours (maximum 19.0 hours) and 7.4 ± 3.8 hours (maximum 14.9 hours) and II period 79 ± 53 min 185 min) and 45 ± 43 min (131 min).

In February 1988, the Committee on obstetrics and the use of obstetric forceps, taking into account the data of cardiotocography, recommended not to exceed the duration of the II period of labor over 2 hours, the so-called "2-hour rule". Studies E. Fridman (1978) also showed that the II period of labor for 2 hours is observed in 95% of parturient women. In the case of miscarriages, the duration of the second stage of labor for more than 2 hours leads to an increase in perinatal mortality. In this regard, obstetric forceps or vacuum extractor is used when the II period of childbirth is more than 2 hours. The authors are not advocates of this rule, when there is no progress of head advancement through the birth canal and there is no fetal distress according to cardiotocography. Epidural analgesia significantly increases the overall duration of labor in both primiparous and repetitious. I period of labor is prolonged on average by 2 hours and II period by 20-30 minutes, which agrees with the data of De Vore, Eisler (1987).

Nesheim (1988), in the study of the duration of labor in 9703 parturient women, showed that in the primiparous, the total length of labor was 8.2 h (4.0-15.0) and in the re-birth, 5.3 h (2.5-10.8 h ). The duration of induced labor was 6.3 (3.1-12.4 hours) and 3.9 (1.8-8.1 hours), respectively, that is, they decreased on average by 2 hours and 1.5 hours, respectively, while the total duration of normal birth in primiparous for 3 hours longer than in the re-birth.

It is important to emphasize that the duration of labor has a positive correlation with the weight of the fetus, the duration of pregnancy, the weight of the pregnant woman during pregnancy and the weight of the woman before pregnancy. A negative correlation was found with the growth of the mother. In addition, the increase in weight for every additional 100 g prolongs labor for 3 minutes, increasing the growth of the mother by 10 cm shortens labor for 36 minutes, each week of pregnancy prolongs labor for 1 minute, each kilogram of body weight prolongs labor for 2 minutes and each kilogram of weight body before pregnancy - for 1 min.

The length of labor in the anterior form of the occipital presentation in primiparas was 8.2 (4.0-15.0 h) and in the recurrent sibling - 5.3 (2.5-10.8 h). In the back view of the occipital presentation, respectively, 9.5 (5.1-17.2 hours) and 5.9 (2.9-11.4 hours). A number of factors can play a role in the passage of the fetus along the birth canal (weight of the fetus and posterior view of the occipital presentation) especially in the primiparous; they do not matter a lot in re-birth. With extensor head presentations (anterolateral, frontal, facial), the length of labor was, respectively, in the first and the re-rooted: 10.0 (4.0-16.2 h) and 5.7 (3.3-12.0 h); 10.8 (4.9-19.1 hours) and 4.3 (3.0-8.1 hours); 10.8 (4.0-19.1 hours) and 4.4 (3.0-8.1 hours). Pelvic presentations do not prolong delivery and are 8.0 (3.8-13.9 hours) and 5.8 (2.7-10.8 hours), respectively.

In a number of modern works, the duration of the second stage of labor and the factors affecting its duration have been studied. It is significant that earlier studies of this problem in modern works have undergone a significant correction. Piper et al. (1991) showed that epidural analgesia affects the duration of the II period and is 48.5 min, and without analgesia - 27.0 min. Parity also affects: 0-52.6 minutes, 1-24.6 minutes, 2-22.7 minutes and 3-13.5 minutes. The duration of the active phase of labor also affects the duration of period II - less than 1.54 hours - 26 minutes; 1.5-2.9 hours - 33.8 minutes; 3,0-5,4 h -41,7 min; more than 5.4 hours - 49.3 minutes. Affects also the increase in body weight during pregnancy: less than 10 kg - 34.3 min; 10-20 kg - 38.9 minutes; more than 20 kg - 45.6 minutes. Newborn weight: less than 2500 g - 22.3 min; 2500-2999 g - 35.2 min; 3000-3999 g - 38.9 min; over 4000 grams - 41.2 minutes.

Paterson, Saunders, and Wadsworth (1992) studied in detail the effect of epidural analgesia on the duration of period II compared to maternal patients without epidural analgesia on a large clinical material (25,069 women giving birth). It was found that in primiparas without anesthesia the duration of the II period was 58 (46) min, with anesthesia - 97 (68) min. The difference was 39 min (37-41 min). In the reproducible, respectively, 54 (55) and 19 (21) min. The difference in the duration of the II period was 35 min (33-37 min). Taking into account the parity, the duration of the II period was the following (with epidural analgesia): 0-82 (45-134 min); 1 - 36 (20-77 min); 2-25 (14-60 min); 3 - 23 (12-53 min); 4 or more births - 9-30 minutes. Without epidural analgesia, respectively: 45 (27-76 min); 15 (10-25 min); 11 (7-20 min); 10 (5-16 minutes); 10 (5-15 min).

An important issue is also the determination of the time intervals of the II period and its relationship to the neonatal and maternal morbidity. This issue is devoted to the work of English authors, based on the analysis of materials from 17 clinics and covering 36 727 births in the region for 1988. A detailed analysis was conducted in 25,069 pregnant women and parturient women with a gestation period of at least 37 weeks gestation. It was found that the duration of the II period of labor is significantly associated with the risk of obstetric hemorrhages and infection in the mother and a similar risk is observed in operative labor and at a fetus weight of more than 4000 g. Moreover, fever in childbirth gives more complications of an infectious nature in the postpartum period than the duration of the II the period of childbirth. Very important is the provision that the duration of period II is not associated with low assessments on the Apgar scale or with the use of special care for newborns. Prominent obstetrician of the XIX century Dennan (1817) recommended a 6-hour duration of the II period of labor, before the use of obstetric forceps. Harper (1859) recommended more active delivery. De Lee (1920) proposed a preventive episiotomy and the use of obstetric forceps to prevent fetal damage. Hellman, Prystowsky (1952), one of the first to point out the increase in mortality in newborns, obstetric hemorrhages and postpartum infection in the mother with a duration of II period of labor over 2 hours. In addition, Butler, Bonham (1963), Pearson, Davies (1974) acidosis in the fetus with a duration of II period of labor over 2 hours.

Over the past 10-15 years, there has been a revision of these provisions on the risk to the mother and fetus II period of labor. So, Cohen (1977) studied more than 4,000 women and did not reveal an increase in perinatal mortality or low estimates of neonatal Apgar scores at the duration of the II period of labor up to 3 hours, and epidural analgesia, despite the prolongation of the II period, does not adversely affect the pH of the fetus, and, if the position of the parturient woman on the back is avoided, it is possible to prevent acidosis in the fetus.

The authors make an important conclusion that the duration of period II up to 3 hours does not give any risk to the fetus.

Thus, on the one hand, the management of births with reflection on the chart (partogram) allows you to identify the boundaries of alertness and take timely action. The graphical analysis of labor activity proposed in 1954 by EA Fridman reflects the dependence of the opening of the cervix and the advancement of the fetal head on the duration of labor, allowing to reveal possible deviations from the norm in them. These include:

• prolongation of the latent phase;
• delay in the active phase of cervical dilatation;
• delay in lowering the head;
• prolongation of the phase of delayed opening of the throat of the uterus;
• stop the opening of the uterine throat;
• delay in moving the head and stopping it;
• rapid expansion of the cervix;
• rapid head advance.

On the other hand, there are conflicting views about the impact of the position of the parturient woman at the time of delivery on the fetal condition. Mizuta studied the effect of the position in which the woman in labor is at labor (sitting or lying on her back), on the condition of the fetus. The condition of the fetus and then of the newborn was assessed based on the analysis of heart rate, duration of labor, Apgar scores, CBS blood of the umbilical cord blood vessels, catecholamine content in the blood of the umbilical vessels, and heart rate in the newborn. It was found that in primiparous women the frequency of application of vacuum extraction of the fetus and depression of the newborn is much less often when sitting. In multiply-fed women, the blood gas content of the umbilical cord arteries was significantly better in the supine position.

An analysis of the data presented shows that none of the positions of the parturient child in labor can be considered more favorable than others.

The features of the clinical course and contractile activity of the uterus during normal delivery have been studied. One of the most important indicators of the course of labor is the duration of the generic act by period and the total length of labor. At present, it is believed that the duration of normal delivery is 12-14 hours in primiparas and 7-8 hours in materigils.

According to our study, the total duration of labor in the primipara was 10.86 + 21.4 min. They are preceded by an average of 37% of cases with a normal preliminar period with a duration of 10.45 ± 1.77 min. The duration of the first stage of labor is 10.32 + 1.77 min, the II period is 23.8 + 0.69 min, the III period is 8.7 ± 1.09 min.

The total length of labor in the re-birth is 7 h 18 min ± 28,0 min. They are preceded in 32% by a normal preliminar period with a duration of 8.2 ± 1.60 minutes. The duration of the first stage of labor is 6 h 53 min ± 28.2 min, II period 16.9 + 0.78 min and III period 8.1 ± 0.94 min.

Another important indicator of the clinical course of labor is the rate of cervical dilatation.

In the first stage of labor, the rate of cervical dilatation has the following picture. The rate of cervical dilatation at the onset of labor before opening the uterine throat to 2.5 cm is 0.35 ± 0.20 cm / h (latent phase of labor); with an opening from 2.5 to 8.5 cm - 5.5 ± 0.16 cm / h in the repetitious and 3.0 + 0.08 cm / h in the primipara (active phase of labor); with the opening from 8.5 to 10 cm there is a phase of slowing down of labor.

At present, the dynamics and rate of opening of the uterine throat is somewhat different, which is due to the use of various medications that regulate labor activity (antispasmodics, beta-adrenomimetics, etc.). Thus, in primiparas, the rate of opening of the cervix for the period from the onset of labor to the opening of the uterine pharynx by 4 cm is 0.78 cm / h, in the period from 4 to 7 cm, 1.5 cm / h, and from 7 to 10 cm - 2.1 cm / h. In the re-birth, respectively: 0.82 cm / h, 2.7 cm / h, 3.4 cm / h.

The contracting activity of the uterus during normal delivery has the following features. The frequency of contractions during all births does not change significantly and amounts to 4.35 ± 1.15 contractions for 10 min with the shortened cervix of the uterus, and by the end of labor with the opening of the uterine pharynx by 8-10 cm - 3.90 ± 0.04 contractions per 10 min. Confidence intervals are in the range from 2.05-4-6.65 to 3.82-4-3.98 bouts in 10 minutes.

As the birth progresses, the phenomenon of the "triple descending gradient" is observed, retained during normal delivery during opening of the uterine pharynx from 2 to 10 cm in 100%, with a shortened neck in 33%.

The temporal indices of the contractile activity of the uterus (the duration of contraction and relaxation of the uterus, the duration of the contraction, the intervals between contractions, of the uterine cycle) increase with the progression of labor and decrease from the bottom to the body and then to the lower segment of the uterus, with the exception of the interval between contractions, which increases from the bottom to lower segment. The duration of uterine contraction is less than the duration of relaxation.

[1], [2], [3], [4], [5], [6], [7], [8], [9]