Obstetric tactics in the management of preterm labor

The problem of protecting the health of mothers and children is considered an important component of health care, which is of primary importance for the formation of a healthy generation of people from the earliest period of their lives. Premature birth is one of the most important issues of this problem. The relevance of premature birth is due to the fact that they determine the level of perinatal morbidity and mortality.

Premature babies account for 60-70% of early neonatal mortality and 65-75% of infant mortality; stillbirths in premature births are observed 8-13 times more often than in full-term births.

Perinatal mortality of premature infants is 33 times higher than that of full-term infants.

The problem of premature births also has a psychosocial aspect, since the birth of a disabled child, his illness or death is a severe mental trauma. Women who have lost children feel fear for the outcome of a subsequent pregnancy, a sense of their own guilt, which ultimately leads to a noticeable decrease in their vital activity, conflicts in the family, and often to the refusal of pregnancy. In this regard, the problem of premature births has not only medical, but also great social significance.

In our country, premature birth is considered to be birth that occurs between 28 and 37 weeks of pregnancy; fetal weight is 1000 g. According to WHO recommendations, perinatal mortality is recorded from 22 weeks of pregnancy with a fetal weight of 500 g or more.

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Risk factors for preterm birth

Based on the clinical and clinical-laboratory analysis of the outcome of premature birth for the mother and fetus in 1000 pregnant women, we have established that the risk factors for premature birth are both socio-demographic: unsettled family life, low social status, young age; and medical: every third woman with premature birth is a primigravida, risk factors include previous abortions, premature births, spontaneous miscarriages, urinary tract infections, inflammatory diseases of the genitals. An important role in the occurrence of premature birth is played by the complicated course of this pregnancy, in the structure of complications, the threat of termination of pregnancy prevails. A special place belongs to infections suffered during pregnancy (ARI and other viral infections). However, these factors do not predict the outcome of premature birth for the fetus.

Risk factors for perinatal morbidity and mortality in preterm birth include the gestational age and weight of the fetus, and the characteristics of the course of preterm birth itself. These factors include abnormal position and presentation of the fetus, including breech presentation, detachment of a normally or low-lying placenta, rapid or precipitous labor, which increases the risk of perinatal mortality by 5 times compared to uncomplicated preterm birth in cephalic presentation. Premature rupture of membranes contributes to the development of preterm birth in 25-38% of cases.

Medication support for premature birth

At present, certain successes have been achieved in the fight against threatening premature births thanks to the use of drugs in obstetric practice that suppress the contractile activity of the uterus. The most widely used in modern conditions are beta-mimetics or tocolytics, a group of substances that specifically act on beta-receptors and cause relaxation of the uterus.

Tocolytic drugs may cause side effects and complications: palpitations, decreased blood pressure (especially diastolic), sweating, tremor, anxiety (agitation), nausea, vomiting, chills, headache, flatulence. Side effects and complications are usually associated with an overdose of the drug and very rarely with its intolerance. Therefore, for therapeutic purposes, it is necessary to reduce the dose or stop administering tocolytics. When treating with beta-mimetics, it is necessary to monitor the heart rate, blood pressure, and blood sugar levels. To eliminate the side effects of beta-mimetics, they are combined with phenoptin 0.04 (1 tablet) 3-4 times a day. This drug, being a calcium antagonist, not only removes the side effects of beta-mimetics, but also reduces the contractile activity of the uterus, enhancing their effect. A reduction in the dosage of medications can be achieved by combining drug therapy with physiotherapy - magnesium electrophoresis with sinusoidal modulated current (SMC). Among modern beta-mimetics, the domestic drug Salgim attracts attention. The peculiarity of this drug is that the beta particle is located on the molecule of succinic acid, an important component of the "breathing" of the cell. Therefore, there are fewer side effects when taking Salgim than with other beta-mimetics, and the effectiveness of the therapeutic effect is the same. The effectiveness of beta-mimetics is 86%.

In case of threat of miscarriage manifested by increased uterine tone, a scheme for using indomethacin, an inhibitor of prostaglandin synthesis, has been developed. Indomethacin is prescribed in a dose of 200 mg per day in tablets or suppositories on the 1st day, 50 mg 4 times in tablets (in suppositories, 100 mg 2 times), 2-3 days, 10 mg every 8 hours, 4-6 days, 50 mg every 12 hours, 7-8 days, 50 mg at night. The total dose should not exceed 1000 mg. The duration of the course of treatment is 5-9 days. Contraindications for the use of indomethacin are gastrointestinal diseases, bronchial asthma. Inhibition of uterine contractility begins 2-3 hours after taking the drug and is expressed in a decrease in tone, a gradual decrease in the amplitude of contractions. Complete normalization of the uterus occurs 3-4 days after the start of therapy. The effectiveness of indomethacin is 72%.

The drug does not have a negative effect on the fetus in the indicated doses. The effectiveness of indomethacin depends on the gestational age and the severity of changes in the cervix. If the threat of miscarriage is at a stage when the cervix is shortened or smoothed, indomethacin is less effective than beta-mimetics. If the contractile activity of the uterus is characterized by high uterine tone, and the cervix is preserved, then the effectiveness of indomethacin is not inferior to beta-mimetics. The side effects of indomethacin are less pronounced than those of beta-mimetics and can be in the form of headache, allergic rash, pain in the gastrointestinal tract.

To consolidate the effect, it is advisable to use a combination of indomethacin with magnesium electrophoresis (SMT).

Therapy for threatened miscarriages and premature births with intravenous drip infusion of 2% magnesium sulfate solution at a dose of 200 ml is carried out for 1 hour in a course of treatment of 5-7 days. Tocolytic therapy with magnesium sulfate does not have a negative effect on the fetus, reduces the mother's blood pressure, increases diuresis, and has a favorable sedative effect. However, the effectiveness is lower than with beta-mimetics and indomethacin, and is 67%.

To treat threatening premature birth, it is necessary to use more non-drug and physiotherapeutic means of influencing the uterine muscles. Electrorelaxation of the uterus is performed.

In case of a threat of premature birth, an integral part of therapy is the prevention of respiratory distress syndrome in newborns by prescribing glucocorticoid drugs to the pregnant woman.

Under the influence of glucocorticoids administered to the pregnant woman or directly to the fetus, more rapid maturation of the lungs is observed, as accelerated synthesis of surfactant occurs.

Pregnant women are prescribed 8-12 mg of dexamethasone per course of treatment (4 mg 2 times a day intramuscularly for 2-3 days or in tablets of 2 mg 4 times on the first day, 2 mg 3 times on the second day, 2 mg 2 times on the third day). Prescribing dexamethasone to accelerate the maturation of the fetal lungs makes sense when therapy aimed at maintaining pregnancy does not give a stable effect and premature labor occurs after 2-3 days. Since it is not always possible to predict the success of the therapy in premature labor, corticosteroids should be prescribed to all pregnant women who are administered tocolytic agents. Contraindications for glucocorticoid therapy are: gastric ulcer and duodenal ulcer (intramuscular route of administration can be used), stage III circulatory failure, endocarditis, nephritis, active tuberculosis, severe forms of diabetes, osteoporosis, severe form of nephropathy.

In case of combined therapy with beta-mimetics and glucocorticoids in case of their intolerance or overdose, cases of development of pulmonary-cardiac insufficiency with pulmonary edema have been described. To prevent these severe complications, strict control of the pregnant woman's condition and all hemodynamic parameters is necessary.

Prevention of respiratory distress syndrome makes sense at 28-33 weeks of gestation. At earlier gestation periods, antenatal maturation of the lungs requires longer use of the drug. Although repeated courses of glucocorticoids are not very effective. In cases where it is not possible to prolong pregnancy, it is necessary to use surfactant to treat respiratory distress syndrome in the newborn. Antenatal prevention of respiratory distress syndrome using surfactant administered into the amnion is usually ineffective. After 34 weeks of gestation, the fetal lungs already have enough surfactant and there is practically no need for prevention of respiratory distress syndrome.

In order to reduce birth trauma during the expulsion period, the benefit is provided without perineal protection. The midwife or doctor delivering the child inserts her fingers into the vagina and, by stretching the vulvar ring, facilitates the birth of the fetal head. In women in labor with a highly rigid or cicatricial perineum, a perineal dissection is mandatory to facilitate the eruption of the fetal head.

The baby is received on a special stand, at the level of the mother's perineum. The baby should not be raised or lowered below the level of the uterus, so as not to create hyper- or hypovolemia in the newborn, which can cause difficulties in its cardiac activity. The baby must be received in warm diapers. It is advisable to separate it from the mother within the first minute after birth and, if necessary, begin resuscitation measures (carefully, gently, preferably in an incubator). Premature babies are contraindicated in the administration of drugs - respiratory stimulants (lobedin hydrochloride, caffeine), as they can cause convulsions.

Prevention of bleeding in the afterbirth and early postpartum periods is carried out using the standard method (intravenous administration of methylergometrine or oxytocin).

Clinical manifestations of rapid preterm labor are frequent, painful, prolonged contractions. Contractile activity of the uterus during rapid preterm labor or labor complicated by excessively strong labor is characterized by a number of features: an increase in the rate of cervical dilation exceeding 0.8-1 cm/hour in the latent phase and 2.5-3 cm/hour in the active phase of labor, a frequency of contractions of 5 or more in 10 minutes, the intensity of contractions is more than 5 kPa, uterine activity in Alexandrian units is 2100 AU in the latent phase and 2430 AU in the active phase of labor.

To predict rapid premature labor, upon admission of patients, tocograms are recorded for 10-20 minutes to assess the frequency of contractions, their intensity, and a repeated vaginal examination is performed after 1 hour to assess the rate of cervical dilation. If the parameters for assessing uterine contractility and the dynamics of cervical dilation fit into the above criteria, then rapid or precipitous labor can be expected.

Correction of contractile dysfunction during rapid premature labor is carried out by intravenous drip administration of partusisten (0.5 mg partusisten in 250-300 ml of 0.9% physiological sodium chloride solution).

For a preliminary assessment of the uterine response to the administration of the drug, during the first 10 minutes, partusisten is administered at a dose of 0.8 mcg/min (10 drops per 1 minute).

In case of discoordinated labor, this dose is sufficient to normalize it. In case of excessively active labor, rapid labor, the dose of partusisten is increased to 1.2-3.0 mcg/min, i.e. up to 40 drops per minute, to suppress excessively high uterine activity, while the contractile activity of the uterus decreases on average after 10 minutes. Then the rate of administration of the drug is gradually reduced until regular contractions appear on the monitor with a frequency of 3-4 contractions per 10 minutes. Tocolysis is continued for at least 2-3 hours under constant hysterography monitoring, since often after rapid withdrawal of the drug, discoordinated contractions or uterine hyperactivity reappear. During the administration of the drug, it is necessary to constantly monitor the pulse and blood pressure.

Tocolysis is stopped when the cervix opens to 8-9 cm, i.e. 30-40 minutes before the expected delivery. In the afterbirth and early postpartum periods, bleeding should be prevented by administering methylergometrine 1.0 or oxytocin 5 U in 300 ml of physiological solution.

During labor, the fetus's condition is assessed based on a dynamic study of the cardiogram. When tocolytics are administered at a rate of 40 drops per minute (1.2-3 mcg/min), the fetus shows an increase in the basal heart rate - up to 160-170 beats per minute with isolated accelerations, which can be explained by the fetus's reaction to the administration of large doses of tocolytics; a decrease in the dose of the administered drug led to the normalization of the fetus's heart rate. However, with threatening hypoxia, the administration of small doses of partusisten led to the normalization of the heart rate. In the doses used, partusisten does not have a negative effect on the condition of the fetus and the newborn.

Management of rapid premature labor under the cover of tocolytics helps to reduce the rate of cervical dilation and a smoother course of labor, normalization of contractile activity of the uterus, which is expressed in a decrease in the frequency of contractions, an increase in pauses between contractions, a decrease in their intensity, along with the absence of a reliable decrease in the duration of contractions.

Intravenous administration of partusisten or other tocolytics, under the control of external tocography, is an effective means for the prevention and correction of labor disorders in premature births, which creates the basis for the prevention of trauma to the premature fetus and thereby reducing perinatal losses.

If weakness of labor occurs in the second stage of labor, endonasal administration of oxytocin can be used. For this, the drug is taken from an oxytocin ampoule containing 5 U of oxytocin with a pipette and administered in a dose of 1-2 drops into each half of the nose after 20 minutes.

The use of the Kresteller method, vacuum extractor in premature fetuses is contraindicated. The use of obstetric forceps is possible at gestation periods of 34-37 weeks.

In case of breech presentation of the fetus, manual assistance should be provided very carefully, using the techniques of classical assistance. It is not advisable to use the Tsovyanov method in case of pure breech presentation in extremely premature babies, due to the easy vulnerability of the premature baby (risk of hemorrhage in the cervical spinal cord).

The issue of cesarean section in case of premature pregnancy is decided individually. Currently, cesarean section up to 34 weeks of gestation is performed for vital indications on the part of the mother. In the interests of the fetus at these gestation periods, the issue of surgery may be raised in case of complicated course of labor in breech presentation, in case of transverse, oblique position of the fetus in women with a burdened obstetric history (infertility, miscarriage) in the presence of intensive neonatal care. In case of necessity of surgical delivery with an undeployed lower segment of the uterus, it is better to use a longitudinal G incision on the uterus, since extraction of the fetus with a transverse incision may be difficult. One of the most frequent complications of premature birth is premature rupture of membranes (PRROM), which is observed in 38-51% of women with premature birth. The possibility of infection with PRROM has a decisive influence on pregnancy management. The risk of infection of the fetus with PROM is higher than that of the mother, which is understandable from the point of view of immature defense mechanisms in the fetus. Currently, expectant tactics are followed in premature pregnancy and PROM, with monitoring for possible infection. Expectant tactics are more preferable the shorter the gestation period, since with an increase in the anhydrous interval, more accelerated maturation of the fetal lung surfactant and a decrease in the incidence of hyaline membrane disease are observed.

The following monitoring of the health of the mother and fetus is necessary: measure the abdominal circumference and the height of the uterine fundus, monitor the quantity and quality of leaking amniotic fluid, measure the pulse rate, body temperature, and fetal heart rate every 4 hours. Determine the leukocyte count every 12 hours, and if leukocytosis increases, look at the leukocyte count. Cervical canal culture and smears are taken every five days. If an immunology laboratory is available, more sensitive tests for detecting incipient infection can be used: assessment of the T-cell link of immunity, the appearance of C-reactive protein, and a spontaneous nitroblue tetrazolium (NBT) test.

Currently, the most informative tests for the occurrence of infection in the fetus are the determination of levels of proinflammatory cytokines in the peripheral blood or il-6 in the mucus of the cervical canal, which increase 2-5 weeks before premature birth. The determination of fibronectin also has prognostic significance. If the level of fibronectin in the discharge of the cervical canal is higher than 27% during premature rupture of membranes, this indicates intrauterine infection.

In case of PRROM, it is necessary to decide on the use of tocolytic therapy, prevention of distress syndrome with glucocorticoids and the use of antibiotics.

Tocolytic therapy may be prescribed to a pregnant woman with PROM in case of threatened and beginning premature labor to prevent respiratory distress syndrome for 48-72 hours, then tocolytic therapy is discontinued and observation continues. In case of the onset of labor, it is no longer suppressed.

The use of glucocorticoids for the prevention of respiratory distress syndrome is one of the difficult issues in PROM and preterm pregnancy, since their use can increase the risk of infectious complications in the mother and fetus. Experience shows that the use of glucocorticoids for the prevention of respiratory distress syndrome should be used before 34 weeks of pregnancy, which has a favorable effect on perinatal mortality rates in premature infants. However, the risk of infectious complications in the mother increases.

The use of antibiotics in patients with PROM is indicated in pregnant women at risk of infectious complications: those taking glucocorticoids for a long time, with isthmic-cervical insufficiency, pregnant women with anemia, pyelonephritis, etc., chronic infections, as well as patients who have had several vaginal examinations due to the obstetric situation even in the absence of signs of infection. For all others, antibiotics should be prescribed at the appearance of the slightest signs of infection, a hormonal background should be created with subsequent labor induction.

Causes of premature birth

Due to the peculiarities of obstetric tactics and different outcomes of labor for the fetus, we consider it appropriate to divide premature births into three periods taking into account the gestational age: premature birth at 22-27 weeks; premature birth at 28-33 weeks; premature birth at 34-37 weeks of gestation.

According to some data, premature births at 22-27 weeks (fetal weight from 500 to 1000 g) are most often caused by isthmic-cervical insufficiency, infection of the lower pole of the fetal bladder and its premature rupture. Therefore, in this group of women, as a rule, there are few primigravidas. The presence of infection in the genital tract excludes the possibility of prolonging pregnancy in most pregnant women. The lungs of the fetus are immature and it is not possible to accelerate their maturation by prescribing medications to the mother in a short period of time. In this regard, the outcome for the fetus in this group is the most unfavorable. Perintal mortality and morbidity are extremely high.

Premature births at 28-33 weeks of gestation (fetal weight 1000-1800 g) are caused by more diverse reasons than earlier premature births. More than 30% of women in this category of births were primigravidas. More than half of the women had the opportunity to use expectant management and prolong pregnancy. Despite the fact that the fetal lungs are still immature, it is possible to achieve their accelerated maturation in 2-3 days by prescribing glucocorticoids. Therefore, the outcome of birth for a fetus of this gestation period is more favorable than in the previous group.

Premature births at 34-37 weeks of gestation (fetal weight 1900-2500 g and more) are caused by even more diverse reasons, the percentage of infected women is much lower than in the previous groups and more than 50% in primigravidas. Most women in this group can use expectant labor management. However, since the fetal lungs are almost mature, there is no need to administer surfactant maturation stimulation agents and prolongation of pregnancy does not significantly change perinatal mortality rates.

The highest percentage of pregnancy terminations occurs between 34 and 37 weeks of pregnancy (55.3%), while between 22 and 27 weeks of pregnancy it is 10 times less frequent (5.7%).

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