| Objective: To study the association between environmental PAHs and missed abortion in early pregnancy, explore the probable risk factors for embryo growth and development and missed abortion on environmental aspect.Methods: Epidemiology and experiment research. First obtain in the number of the abortion operations and the details of the missed abortion patients in each months of 6 recent years of 15 general hospitals and gynaeology and obstetrics hospitals in urban field of tianjin. Compare the differences of the percentage of missed abortion cases in all the abortion operations of each months between months, seasons and heating and nonheating period. Gain the monthly average levels of BaP in January and July from 2001 to 2006 in six national monitoring stations in urban field of tianjin from Environment monitoring centre. Collect the new cases of missed abortion in four general hospitals of tianjin from April to December 2007, and select the control by the rate of one to one according to ages, gravidity, parity and gestational weeks, subjects in control group are women that have the request for abortion operation in normal pregnancy. A questionnaire was administered by trained interviewers with the patients'agreement for information about environmental risk factors contact of wife and husband in and before pregnancy. Draw 2 ml maternal blood using EDTA anticoagulation tube after abortion operation, the sample and the questionnaire were encoded together and storaged in -20℃. Extract maternal blood genome DNA and examine its levels every week. Analyze the difference between BaP-DNA adducts levels of case and control group examined by high-performance liquid chromatography-fluorescence method (HPLC) by using signed-rank test. Analyze probable environmental risk factors for maternal blood adducts and missed abortion in separate models, explore probable influence factors for maternal adducts and missed abortion and its risk by multiple linear regression and logistic regression model respectly.Results: 1 BaP levels of January in recent five years in tianjin area are significantly higher than that of July (P=0.0082), the percentage of missed abortion cases in all the abortion operations of January in the 15 urban field hospitals is obviously higher than that of July. In addition, the case percentage has seasonal variation, Analyzing by the time of visit, we have found that the missed abortion case percentage in spring (2.37%)is the highest one, then comes winter (2.16%), summer (1.82%) and autumn (1.54%) in order. Winter and spring case percentage is significantly higher than summer and autumn (P=0.001).Women conceived during winter (2.29%), backwards to the visit, whose case percentage is the highest one, then comes autumn (2.01%), spring (1.92%) and summer (1.72%) in order, which indicates that the case percentage of heating period is higher than that of nonheating period.2 Significant difference is not found between the two groups by analyzing the extracted genome DNA of gained 112 maternal blood samples with DNA level examined (P=0.407). The lowest BaP-DNA adducts level detected by HPLC is 1.81ng/ml, the average of maternal adducts level is 4.3±4.0 adducts/108nucleotides. Women smoked and with occupational exposure are excluded. A total of 104 samples were included in this case-control study at last. we found that BaP-DNA adducts levels of the case group (6.3±4.7 adducts/108nucleotides) were significantly higher than that of the control group (2.4±1.4 adducts/108nucleotides)(P=0.000). Maternal adducts level was probably a significant risk factor for missed abortion (OR=3.52, 95%CI 1.44-8.62), while maternal education was a protective factor(OR=0.55, 95%CI 0.32-0.94)afer controlling potential confounders including maternal education, household monthly income.3 After analyzing the questionnaires, we found that maternal adducts level was negatively and significantly correlated with distance from residence to the nearest roadway by using spearman's rank correlation method (r=-0.212,P=0.035), the nearer the distance from the residence to the roadway was, the higher maternal blood BaP-DNA adducts levels were. After selecting all potential effective factors, we found that cooking during pregnancy, traffic jam nearby the residence were positively and significantly correlated with maternal adducts, while the correlation between maternal adducts and maternal education was negative by multiple linear regression analysis. The regression equation is Y=2.205+1.024X1-0.95X2+1.064X3. The most effective factor for maternal adducts was traffic jam nearby the residence(X3), then came with cooking during pregnancyand (X1) and maternal education (X2) .In separate model, we found that lower education and income, toxic matter (pesticide, paint) contact of wife and husband during the three months before pregnancy, fitment history during pregnancy, more daily traffic hourstraffic jam nearby, roast food eating, cooking during pregnancy and perm in early pregnancy probably had adverse effects on embryo growth and development. We found that fitment history in early pregnancy(OR=7.16,95%CI 1.98-25.81), toxic matter (pesticide, paint) contact of husband during the three months before pregnancy(OR=5.87, 95%CI 1.15-29.82), more daily traffic hours(OR=2.67, 95%CI 1.16-6.15), cooking frequently during pregnancy(OR=1.46, 95%CI 1.05-2.03)were the probable risk factors for missed abortion by selecting all the correlated variables to the logistic regression model, while maternal education was a protective factor for missed abortion.Conclusion: 1 BaP-DNA adducts in maternal blood was a significant risk factor for missed abortion in early pregnancy. 2 Maternal education, cooking frequently during pregnancy and traffic jam nearby the residence may have effects on maternal BaP-DNA adducts by different degrees. 3 Daily traffic hours, cooking frequently during pregnancy, fitment history in early pregnancy and toxic matter (pesticide, paint) contact of husband during the three months before pregnancy may have adverse effects on embryo growth and development, while maternal education was a protective factor.
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