Assessment of the impact of COVID-19 experienced at different stages of gestation on perinatal outcomes and structural changes in the placenta

BACKGROUND: At the beginning of the pandemic COVID-19, the attention of obstetricians and gynecologists was focused on studying the impact of SARS-CoV-2 on obstetric and perinatal outcomes. Currently, the dynamics of mutations in genes encoding SARS-CoV-2 proteins determines the emergence of a large number of new strains of the virus that are highly virulent. Given this fact, the problem of assessing the impact of COVID-19 on pregnancy outcomes also remains relevant. AIM: The aim of this study was to assess the impact of the novel coronavirus infection (COVID-19) transmitted at different stages of gestation on perinatal outcomes and structural changes in the placenta. MATERIALS AND METHODS: In 2022–2023, a prospective analysis of 113 cases of childbirth in women who had the novel coronavirus infection during pregnancy was carried out in obstetric institutions in Novosibirsk. The total sample of subjects was divided into three study groups using cluster analysis. Group 1 included 25 women who had SARS-CoV-2 at a gestation period of up to 16 weeks; Group 2 consisted of 61 patients who underwent COVID-19 at gestation period of 17 to 34 weeks; and Group 3 comprised 27 pregnant women in whom COVID-19 was detected after 34 weeks of pregnancy. The control group included 65 pregnant women who had a negative smear test result for SARS-CoV-2. Pathological examination of the placenta included macro- and microscopic studies. Statistical processing of the results was carried out using the IBM SPSS Statistics Version 25.0 program. RESULTS: The most common fetal distress was observed in patients of Groups 1 and 2 (p = 0.002). We found an inverse correlation between the gestational age at which a woman suffered coronavirus infection and the volumetric density of capillaries and intervillous fibrinoid, as well as the percentage of formation of the syncytial-capillary membrane and villi with symplastic buds. On the contrary, a direct correlation between the gestational age and the volumetric density of connective tissue was found. Intervillusitis was more often observed in the placentas of women of Groups 1 and 2. Histitocytic infiltration was characteristic of the placentas of patients of Group 2. CONCLUSIONS: The frequency of adverse perinatal outcomes and the intensity of structural changes in the placenta depend on the gestation period in which the patient suffered the novel coronavirus infection. The most significant structural changes in the placenta were detected in patients of Group 2.