Objective This study explored the association between air pollution exposure and birth weight by using the multilevel linear model,after controlling related meteorological factors and individual differences of both mothers and babies.Methods Women of childbearing age who were pregnant in Xi'an from 2010 to 2013,were selected as objects of this study.Multistage random sampling method was used to select 4 631 subjects followed by a self-designed questionnaire survey.Data related to quality of air and meteorology were gathered from routine monitoring system.Gestational age and date of birth,together with the average levels of air pollution were calculated for each trimester on each mother,and then the impact of air pollution on birth weight was assessed.A multilevel linear model was employed to investigate the association between the levels of exposure to air pollution by birth weight.Confounding factors were under control.We established three models in this study:Model 1 which involving the variable of air pollution exposure.Model 2 was adjusted for variables in Model 1 plus some other individual differences of both mother and baby.Model 3 was adjusted for variables in Model 2 plus meteorological factors.Results There were significant differences seen in birth weight within the subgroups of gender,gestational age,mother's reproductive age,maternal education,residential areas and family incomes (P＜0.01) of the infants.However,there was no difference found in Model 1 (P＞0.05).Data from Model 3 indicated that a decrease of 13.3 g (10.9 g in Model 2) and 6.6 g (5.9 g in Model 2) in birth weight that were associated with an increase of 10 μg/m3 in the average level of NO2 and PM10 during the second trimester;A decrease of 13.7 g (9.8 g in Model 2) in birth weight was associated with an increase of 10 μg/m3 in the average level of NO2 during the third trimester.Conclusion After controlling for meteorological factors,the levels of exposure to NO2 and PM10 during the second trimester and NO2 during the third trimester were negatively associated with birth weight.

Objective To understand the prevalence of birth defects, related diseases and mental status of women during pregnancy in Shaanxi province and to analyse the major risk factors on birth defects and congenital heart disease. Possible association between maternal diseases or mental status and the risk of birth defects, was also explored. Methods A cross-sectional design was used in this study and stratified multistage random sampling method was used. The whole survey was from Jury 2013 to November 2013. Logistic regression method was used to analyze the association between maternal diseases, mental status during pregnancy and birth defects. Results The overall prevalence of birth defects was 195.04 per 10000 in Shaanxi. Among the 29121 mothers participating in this study, 51.1% developed illness and 6.8%"changed their mental status during pregnancy. After adjusting all the confounding factors, results showed that, histories of cold", fever, and intrahepatic cholestasis were (OR=1.33, 95%CI:1.10-1.61, OR=1.54, 95%CI:1.09-2.16, and OR=32.77, 95%CI:4.08-263.04) respectively, during pregnancy that related to birth defects. Self-reported unstable mental status (OR=1.60, 95%CI: 1.19-2.15) and family friction (OR=2.07, 95%CI: 1.12-3.79) were both related to the birth rates. Histories of cold and fever (OR=1.59, 95%CI:1.28-1.98;OR=1.43, 95%CI:1.48-4.00), during early pregnancy, unstable mental status during mid-pregnant period (OR=1.52, 95%CI:1.05-2.19), unstable mental status during late-pregnant period (OR=1.63, 95%CI:1.05-2.19) and family friction during late-pregnant period (OR=2.89, 95%CI:1.16-7.20) were found to be related to birth defects. Compared with those without history of cold, those with the history of cold during first (OR=1.24, 95%CI: 1.02-1.52) and second stages (OR=2.06, 95%CI: 1.30-3.26) of pregnancy were more likely to bear fetus with birth defects. Compared with those without these histories, those with histories of fever (OR=1.49, 95%CI:1.04-2.13), emotional problem (OR=1.71, 95%CI:1.19-2.45) and related diseases (OR=2.67, 95%CI: 1.32-5.39) during the first period of pregnancy were more likely to bear fetus with birth defects. Conclusion The incidence of birth defects in Shaanxi was high. Histories of cold, fever, unstable mental status and family friction during pregnancy, seemed to have increased the risks of bearing child with birth defects.

【Objective】 To compare the clinical features of Omicron and Delta cases, so as to provide scientific basis for the prevention and treatment of COVID-19. 【Methods】 The case-control study method was used to retrospectively analyze the clinical data of the Omicron cases admitted to the designated hospital for the treatment of COVID-19 in Xi’an from December 2021 to January 2022. and the Delta cases admitted during the same period were used as the control group. The demographic data, epidemiological history, vaccination status, clinical characteristics, laboratory tests, nucleic acid and antibody levels, and outcomes of patients in the two groups were collected and compared. 【Results】 A total of 21 patients were included in the study, 5 were Omicron patients and 16 were Delta cases. The mean age of the patients in the two groups were (38.20±15.07) and (37.69±10.39) years, respectively.The time interval between the last vaccination and the diagnosis was (145.40±77.92) days and (159.00±99.74) days, respectively. For the initial symptoms, the patients with Omicron were mainly characterized by throat discomfort (3, 60%), cough and sputum (2, 40%), and the patients with Delta were mainly characterized by throat discomfort (5, 31.25%), fatigue (5, 31.25%), cough and sputum (4, 25%). On admission, laboratory tests showed that 60% of Omicron patients had low lymphocytes and elevated erythrocyte sedimentation rate, and 50% of patients in the delta group had elevated hemoglobin. The Ct values of ORFlab gene, N gene and E gene with Omicron were lower than those with Delta. And the difference of E gene between the two groups was statistically significant (t=-2.711, P=0.024). IgG antibody levels increased in both groups.The time for nucleic acid to turn negative with Omicron was (28.20±5.89) days, and it was (18.50±7.73) days with Delta, and the difference between the groups was statistically significant (t=2.565, P=0.019). The length of hospitalization with Omicron was (30.60±4.88) days, and that with Delta was (22.13±7.81) days, and the difference was statistically significant (t=2.270, P=0.035). 【Conclusions】 The initial symptoms of Omicron patients are mainly throat discomfort, cough and sputum. The clinical manifestations are generally mild. The nucleic acid test Ct value is lower. The time for nucleic acid to turn negative and the time for hospitalization are longer, and the potential infectiousness is stronger. Those eligible for vaccination should complete the full course of vaccination and booster vaccination as soon as possible. At the same time, the management of "early detection, early reporting, early isolation, and early treatment" should be implemented.