Recurrent miscarriage is most often associated with long-term adverse endogenous effects. The etiological factors of this obstetric pathology are in many respects similar to those in infertility or sporadic interruption of gestation and differ only in lesser severity compared to infertility and a permanent nature, in contrast to the transient effect with spontaneous losses. The main causes of habitual miscarriage include:
• Autoimmune diseases. The proportion of immunological factors in the etiology of pregnancy loss is up to 80%. The most significant autoimmune disorders include antiphospholipid syndrome (APS), sensitization to human chorionic gonadotropin, thyroid hormones, and nuclear antigens. The risk group includes mothers suffering from autoimmune diseases, viral infections (hepatitis C, HIV).
• Alloimmune disorders. Among the alloimmune causes of miscarriage are high histocompatibility of spouses, the predominance of pro-inflammatory cytokines in the blood of the mother and endometrium, and a deficiency of the progesterone-induced blocking factor. The risk group includes women who are married to a blood relative, who have endocrine pathologies with progesterone deficiency.
• Congenital thrombophilia. In a third of pregnant women, recurrent miscarriage is provoked by mutations in factor V Leiden and the prothrombin gene, deficiency of antithrombin III, proteins C and S, and hyperhomocysteinemia. Risk factors: early (up to forty years) thromboembolism, recurrent thrombosis in a woman and her close relatives, thrombotic complications associated with gestation, childbirth and the use of hormonal contraceptives.
• Endocrine disorders. In 8-20% of patients, the cause of losses is luteal phase deficiency, increased secretion of luteinizing hormone, hyperandrogenism, hypothyroidism and decompensated diabetes mellitus. The risk group consists of women with obesity, signs of virilization, late menarche, sharp fluctuations in body weight, oligo- and amenorrhea, menstrual irregularities.
• Endometrial infections. In 87% of patients with miscarriage, persistence in the endometrium of several types of obligate anaerobic flora and viral agents (herpes simplex, cytomegalovirus, Coxsackie, enteroviruses) is noted. The likelihood of endometritis is increased in patients with chronic lower genital tract infection, bacterial vaginosis, induced abortions, and previous uterine surgery.
• Anatomical defects of the uterus. Congenital (duplication of the uterus, saddle-shaped, unicornuate uterus, intrauterine septum) and acquired (submucosal myomatous nodes, intrauterine adhesions) anatomical disorders are the cause of abortion in 10-16% of women. Risk factors for acquired pathologies: endometritis, artificial abortions, surgical interventions on the uterus.
• Pathology of the cervix. Isthmic-cervical insufficiency (ICI) can be anatomical or functional in nature and is involved in recurrent interruptions of gestation in 13-20% of cases. It often develops with hyperandrogenism of any genesis, cervicitis, after a difficult birth (accompanied by ruptures, the use of obstetric forceps), conization of the cervix, hyperovulation induction.
• Genetic abnormalities of the fetus. Usually these are chromosomal aberrations that lead to habitual miscarriage in 3-6% of cases. Among them, monosomy X0 (Shereshevsky-Turner syndrome), various trisomies, polyploidy. Risk factors: closely related marriage, hereditary diseases in the families of the patient and her spouse, the presence of children with congenital defects in a married couple, mental retardation.