Relationship Between Missed Abortion And Exposure To Carbon Monoxide In The Air During Peri-conception Period

Objective: To analyze the relationship between exposure to carbon monoxide in the air during peri-conception period and missed abortion.Method:Analyze the relationship between exposure to carbon monoxide and missed abortion using respective case-control method. Gain the monthly average levels of CO in March,June,September and December from 2001 to 2007 in six national monitoring stations in urban field of tianjin from Environment monitoring centre. The data of case group and control group are form 15 General Hospitals and birth control out-patient clinic in Tiajin in 6 years(2001-2007).The number of missed abortion are 975. In accordance with the age group,we collect the normal pregnancy who requested toabortion as control group . Analysis all data by using SPSS 11.0 software. Analyze the distribution of carbon monoxide in different years,months,heating period and non-heating period by t-test,rank test and Chi-square methods. Find the Characteristics of missing abortion in six major region of Tianjin between 2001 and 2007. Compare the differences of the percentage of missed abortion cases in all the abortion operations of each months between months, seasons and heating and non-heating period. Compare the difference of exposure to CO between case and control group in the month before pregnancy,the month of pregnancy and the month after pregnancy. Analyze the risk of missed abortion exposing to different grades.The logistics regression method is used to analyze the relationship between all factors we got such as ages,frequency of spontanous abortion,gravidity,parity and exposure to CO et al during peri-conception period and missed abortion.Results:1 Compared June,September with December respectively,there have significant difference, the higher was in December.The average concentration of the heating period was significantly higher than non-heating period (P = 0.043). The highest in patients is spontaneous abortion witch is accounted for 2.6%. The percentage of missed abortion in heating period is significantly higher than non-heating period(P=0.000).2 from the interior of morbidity in patients with six district statistics of Tianjin,we found that 20-year-old age -29 in patients with stage of the high incidence of cases(59%).3 To analyze the difference of control group and patients exposuring to carbon monoxide in one month before pregnancy, pregnancy month,one month after pregnancy ,the exposure of one month after pregnancy that have significant differences between the two groups, (P = 0.041).There is no significant differences in the month before pregnancy(P=0.147)and the month of pregnancy(P=0.699).Analyze of Level exposed in one month after pregnancy, there are significant differences in low-exposure group (0-1.3mg/m3) (P=0.037) match to middle-high-exposure group(1.6-2.1 mg/m3) (P=0.027),and low-exposure group (0-1.3mg/m3) match to high-exposure group(1.6-2.1mg/m3).the Morbidity of middle-high-exposure group and high-exposure group is higher than the low-exposure group.Further analysis on risk of the middle-and high-exposure group, the high exposure group with low exposure group respectiy.Of Middle-and high-exposure group, OR = 1.609 (95% CI = 1.029-2.516), it means the incidence risk of missed abortion in Middle-and high-exposure group is 1.609 times higher than the low-exposure group.and of high-exposure group,OR = 1.662 (95% CI = 1.059-2.608 ), indicating that in high- exposure groups,the incidence risk is 1.662 times higher than in the low-exposure group. That is, increased concentrations of carbon monoxide exposure, may increase the risk of incidence4 Analyze the other possible factors that may be associated with missed abortion by logistic regression.Finally result are four factors are relevant to missed abortion,they are maternal age grade(P=0.000,0R=1.646),Frequency of spontaneous abortion(P=0.035,0R=9.370),the exposure to carbon monoxide Level in one month after pregnancy(P=0.038,OR = 1.185),the OR values of three factors are greater than one ,so they are possible risk factors.Production number's OR value(P=0.038,0R=0.299)is less than one ,for possible protective factor. Regression equation was Y=-1.784+0.499X1+2.237X2+0.170X3-1.208X4.Conclusion:1 Exposure to higher concentrations of carbon monoxide in the month after pregnancy may increase the risk of missed abortion . The higher they exposed,the higher the risk of missed abortion will be.2 The occurrence of missed bortion is associated with maternal age and the frequency of spontaneous abortion.Older in pregnancy age and more often with spontaneous abortion will increase the risk of missed abortion.