Factors of pregnancy termination

Among the factors of pregnancy termination, pregnancy complications occupy a large place: toxicosis in the second half of pregnancy, abnormalities of placental attachment, premature placental abruption, abnormal fetal position. Of the antenatal bleedings, the most significant are bleedings associated with placenta previa and placental abruption in a normally located placenta, as they are accompanied by high perinatal mortality and are dangerous to the woman's life. The causes of placenta previa or its attachment in the lower parts cannot be considered fully understood.

In recent years, data has emerged that allows us to take a new approach to solving the problem of preventing this dangerous obstetric pathology.

In the general population, the incidence of placenta previa is 0.01-0.39%. According to research, in the first trimester of pregnancy, 17% of women with habitual miscarriage of various origins are diagnosed with placenta previa by ultrasound. During pregnancy, in most cases, placenta "migration" is observed, which usually ends in 16-24 weeks of pregnancy.

However, in 2.2% of women, placenta previa remains stable. In 65% of women with chorion previa outside pregnancy, there were pronounced hormonal and anatomical disorders: incomplete luteal phase, hyperandrogenism, genital infantilism, chronic endometritis, intrauterine adhesions. Malformations of the uterus were detected in 7.7% of women. In 7.8% of cases, the first pregnancy was observed after long-term treatment for hormonal infertility.

The course of pregnancy in 80% of women with presentation of the branched chorion was characterized by frequent bloody discharge without signs of increased contractile activity of the uterus.

As the placenta "migrated", the bleeding stopped. However, in women with stable placenta previa, bleeding periodically resumed at all stages of pregnancy. Anemia of varying severity was noted in 40% of them.

Since chorion/placenta previa is often detected in pregnant women with miscarriage, it is necessary to carry out pathogenetically justified rehabilitation therapy outside of pregnancy in preparation for pregnancy.

In the first trimester, if the presentation of the branched chorion is detected, it is necessary to carry out dynamic monitoring using ultrasound and prevent placental insufficiency. In the absence of placental "migration" phenomena, with its stable presentation, it is necessary to discuss the issue with the patient about the regimen, the possibility of rapid hospitalization in the event of bleeding, the possibility of staying in a hospital setting, etc.

It cannot be said that the problem of premature detachment of a normally located placenta has not attracted researchers. However, many aspects of this problem remain unresolved or controversial due to conflicting views on many issues of this severe pathology.

There is conflicting information about the effect of the area of the placenta separated from the uterine wall on the condition of the fetus, about structural and morphofunctional changes, and about the interpretation of data.

The views on the nature of myometrial changes in this pathology are controversial. The frequency of this pathology in the population fluctuates from 0.09 to 0.81%. It should be noted that the cause of detachment can be very difficult to establish. Data analysis showed that in 15.5% of women, detachment occurred during toxicosis in the second half of pregnancy or hypertension of another genesis. The rest had polyhydramnios, multiple pregnancy, anemia, and late amniotomy. In 17.2% of pregnant women, it was not possible to identify or even suggest the cause of this pathology. In 31.7% of women, detachment occurred during premature labor, in 50% - preceded the onset of labor. In 18.3% of women with placental abruption, no signs of labor were observed later.

Anomalies of the placenta itself (placenta circumvaelate, placenta marginata) are traditionally associated with premature loss of pregnancy.

Anomalies of the hemochorial placenta do not always accompany chromosomal pathology of the fetus. It is believed that such pregnancy complications as eclampsia, intrauterine growth retardation and frequent placental abruption are pathogenetically linked by a single mechanism - anomaly of the placenta due to the limitation of the depth of invasion. At the point of contact of the placenta with the uterus, there are factors that enhance or limit growth, there is a very delicate balance of cytokines that controls the depth of invasion. Th2, cytokines and growth factors such as colony-stimulating growth factor 1 (CSF-1) and il-3 enhance trophoblast invasion, while Th1 cytokines limit it (through il-12, TGF-β. Macrophages play a regulatory role in this process, limiting the action of il-10 and γ-IFN. The placenta is a developing organ during the first trimester, and if the balance of cytokines is disturbed in favor of such factors as il-12, 1TGF-β, γ-IFN, then these disorders limit trophoblast invasion, while the normal development of trophoblast to the spiral arteries is disrupted and the intervillous space is not properly formed. If the invasion is incomplete, the increased pressure in the maternal spiral arteries can disrupt the thin layer of trophoblast. If the detachment increases, the pregnancy will be lost. If the detachment is partial, then subsequently, placental insufficiency develops with intrauterine growth retardation and pregnancy-induced hypertension.

Apoptosis in the placenta increases with placental development and may play a role in placental development and aging. Premature induction of apoptosis may contribute to placental dysfunction and resulting pregnancy loss. In studies of placentas from women with spontaneous and induced pregnancy loss, significant reductions in proteins that inhibit apoptosis have been found. It is believed that abnormalities in placental protein production may lead to early apoptosis and pregnancy loss.

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