To date, there is no consensus on the pathogenesis of miscarriage. In modern life, human health is signifi cantly infl uenced by environmental factors. In this regard, 37 years after the accident at the Chornobyl nuclear power plant, the question of remote cytogenetic and hereditary eff ects in the off spring of parents aff ected by radiation remains relevant. Ecosystems contaminated with radioactive substances are a source of exposure for humans. Internal irradiation is the cause of reproductive losses. Radiation stress aff ects the course of redox processes in the body. Biochemical indicators are markers of the infl uence of environmental factors on a person. The study is dedicated to determining the state of peroxide hemostasis in the case of miscarriage. Aim: to determine the peculiarities of the functioning of the detoxification system in case of miscarriage due to the accumulation of 137Cs.Material and methods. The fi rst (research) group included women with reproductive losses in anamnesis and signs oftermination of the current pregnancy; the second (control) group included women with an uncomplicated history and course of pregnancy. Additionally, the fi rst group was divided into subgroups according to pregnancy outcomes: А – 38 women who gave birth at 37-40 weeks, despite the complicated course of the current pregnancy, В – 13 women who gave birth at 28-36 weeks + 6 days, С – 9 women who birth at 22-27 weeks + 6 days. The state of peroxide hemostasis in women was studied using biochemical studies. Accumulation of 137Cs with diff erent activity was detected in the placentas of the examined women of both groups using β-spectrometry. Morphological examination of placentas was performed according to the protocol. The severity of placental damage was studied by Olympus BX51 and Axioskop 40 microscopes. Analyzing the results revealed a relationship between biochemical indicators, the activity of 137Cs, and pregnancy scenarios. Statistical data analysis was performed using Microsoft Excel (2016) and Fisher angular transformation. The diff erence between comparative values was considered signifi cant at p < 0.05 (probability index greater than 95 %). Permission to conduct research was obtained from the Medical Ethics Committee of the SI «Institute of Pediatrics, Obstetrics, and Gynecology named academic Elena M. Lukyanova of the National Аcademy of Мedical Sciences of Ukraine» (protocol No 3 of 07.06.2017).Scientifi c research work is to «Develop the latest and improve existing technologies for diagnosis, prevention, and treatmentof premature termination of pregnancy in women with miscarriage taking into account the passport of the placenta» (2018-2020). Code VN.20.00.02.18, state registration number 0118U000039, KPKV 6561040.Results. It has been confi rmed that the state of the environment plays a decisive role in the pathogenesis of miscarriage. Ithas been proven that placental dysfunction caused by abnormal oxidative stress due to the action of incorporated 137Cs leads to pregnancy termination. As a result of the depletion of the antioxidant reserve, the compensatory capabilities of the placenta decrease. It was established that activity in the placenta up to 1.0 Bq/kg of 137Cs does not aff ect the course of gestation. The compensatory capacity of the placenta remains preserved even with the accumulation of 1.1 to 4.4 Bq/kg of 137Cs. At the same time, it is possible to prolong the pregnancy until the term of timely delivery. Internal irradiation with an activity of 4.5-10.4 Bq/kg of 137Cs causes damage to the stroma of the maternal surface of the placenta and premature birth at 28-36 weeks + 6 days. At the same time, newborns are viable due to the preservation of compensatory reactions in the placenta. Accumulation of more than 10.4 Bq/kg of 137Cs causes antenatal death of the fetus and early premature birth due to damage to maternal and fetal structures of the placenta. An increase in the content of malondialdehyde and a decrease in the activity of superoxide dismutase in the blood indicate the severity of radiation damage.Conclusions. Internal exposure to 137Cs disrupts the architecture and functional capacity of the placenta. Extreme eff ectsdepend on the activity of 137Cs, the compensatory capabilities of the placenta, and the pregnant woman’s body. Activation of lipid peroxidation acts as a biochemical amplifi er of radiation exposure. An increase in the blood of malondialdehyde, diene conjugates, and free SH groups is associated with the severity of radiation damage. An early marker of primary placental dysfunction, premature birth, and antenatal fetal loss is an increase in MDA content in the blood by 12.0 % and a decrease in SOD by 6.5 % relative to permissible values. An early marker of exhaustion of the compensatory reserve is an increase in the content of MDA in the blood by 23.3 % and a decrease in SOD by more than 18.2 % relative to the permissible values. Decompensation of adaptation mechanisms in the system «mother- placenta-fetus» leads to antenatal losses.
