Objective:To observe the pregnancy outcomes of patients with unexplained recurrent spontaneous abortion (URSA) after interventional treatment or expectant treatment.Methods:This prospective study followed up 398 patients with recurrent spontaneous abortion from March 2017 to September 2022 in seven hospitals. Among them, 267 patients were diagnosed with URSA, including 124 patients who were initially diagnosed in the interventional treatment hospital and 143 patients who were initially diagnosed in the expectant treatment hospital. All URSA patients were followed up for 33 months. Ongoing pregnancy rates were observed as main outcome indicators.Results:A total of 127 patients became pregnant, and 107 of them had sustained pregnancies, the ongoing pregnancy rate was 84.25% (107/127). The ongoing pregnancy rate was 86.11% (31/36) in the interventional treatment group and 83.52% (76/91) in the expectant treatment group, with no significant difference ( P>0.05). During the follow-up, the ongoing pregnancy rates in the interventional treatment hospital and the expectant treatment hospital were 75.71% (53/70) and 94.74% (54/57), respectively, with a significant difference ( P<0.05). The ongoing pregnancy rate after interventional treatment in the interventional treatment hospital was 82.76% (24/29), which was similar to the 94.00% (47/50) after expectant treatment in the expectant treatment hospital ( P>0.05). Conclusion:The ongoing pregnancy rate of interventional treatment for URSA patients has not been significantly improved, suggesting that it may not be necessary to carry out this treatment.

Objective:To observe the pregnancy outcomes of patients with unexplained recurrent spontaneous abortion (URSA) after interventional treatment or expectant treatment.Methods:This prospective study followed up 398 patients with recurrent spontaneous abortion from March 2017 to September 2022 in seven hospitals. Among them, 267 patients were diagnosed with URSA, including 124 patients who were initially diagnosed in the interventional treatment hospital and 143 patients who were initially diagnosed in the expectant treatment hospital. All URSA patients were followed up for 33 months. Ongoing pregnancy rates were observed as main outcome indicators.Results:A total of 127 patients became pregnant, and 107 of them had sustained pregnancies, the ongoing pregnancy rate was 84.25% (107/127). The ongoing pregnancy rate was 86.11% (31/36) in the interventional treatment group and 83.52% (76/91) in the expectant treatment group, with no significant difference ( P>0.05). During the follow-up, the ongoing pregnancy rates in the interventional treatment hospital and the expectant treatment hospital were 75.71% (53/70) and 94.74% (54/57), respectively, with a significant difference ( P<0.05). The ongoing pregnancy rate after interventional treatment in the interventional treatment hospital was 82.76% (24/29), which was similar to the 94.00% (47/50) after expectant treatment in the expectant treatment hospital ( P>0.05). Conclusion:The ongoing pregnancy rate of interventional treatment for URSA patients has not been significantly improved, suggesting that it may not be necessary to carry out this treatment.

Landfill is one of the important sources of carbon tetrachloride (CT) pollution, and it is important to understand the degradation mechanism of CT in landfill cover for better control. In this study, a simulated landfill cover system was set up, and the biotransformation mechanism of CT and the associated micro-ecology were investigated. The results showed that three stable functional zones along the depth, i.e., aerobic zone (0-15 cm), anoxic zone (15-45 cm) and anaerobic zone (> 45 cm), were generated because of long-term biological oxidation in landfill cover. There were significant differences in redox condition and microbial community structure in each zone, which provided microbial resources and favorable conditions for CT degradation. The results of biodegradation indicated that dechlorination of CT produced chloroform (CF), dichloromethane (DCM) and Cl^- in anaerobic and anoxic zones. The highest concentration of dechlorination products occurred at 30 cm, which were degraded rapidly in aerobic zone. In addition, CT degradation rate was 13.2-103.6 μg/(m²·d), which decreased with the increase of landfill gas flux. The analysis of diversity sequencing revealed that Mesorhizobium, Thiobacillus and Intrasporangium were potential CT-degraders in aerobic, anaerobic and anoxic zone, respectively. Moreover, six species of dechlorination bacteria and eighteen species of methanotrophs were also responsible for anaerobic transformation of CT and aerobic degradation of CF and DCM, respectively. Interestingly, anaerobic dechlorination and aerobic transformation occurred simultaneously in the anoxic zone in landfill cover. Furthermore, analysis of degradation mechanism suggested that generation of stable anaerobic-anoxic-aerobic zone by regulation was very important for the harmless removal of full halogenated hydrocarbon in vadose zone, and the increase of anoxic zone scale enhanced their removal. These results provide theoretical guidance for the removal of chlorinated pollutants in landfills.
Bacteria/metabolism* ; Biodegradation, Environmental ; Carbon Tetrachloride/metabolism* ; Methane/metabolism* ; Waste Disposal Facilities