Pnm-18: Maternal Exposure to Ozone, Nirogen Dioxide, Sulfur Dioxide and Spontaneous Abortion

Background: Adverse pregnancy outcomes (low birth weight, prematurity and intrauterine growth retardation) are associated with exposure to urban air pollution. Experimental data have also shown that such exposure elicits adverse reproductive outcomes. We examined association between spontaneous abortion of the first trimester of pregnancy and ambient concentrations of Ozone, Nirogen Dioxide and Sulfur Dioxide in Tehran. Materials and Methods: This study is a case-control research that was conducted on 148 spontaneous abortion (case group) and 148 pregnant women (control group). Samples were collected randomly from 10 hospitals in Tehran between June 2010 to February 2011 and the correlation between spontaneous abortion and Ozone, Nirogen Dioxide, Sulfur Dioxide as environmental pollutants was investigated. Results: Two groups in the study were highly correlated in participants&#039; age, their husbands&#039; age, age at the first childbirth, educational level, average income of the family, previous delivery type and the interval between deliveries, experience of any previous abortion, body mass index, parity, duration of residence in Tehran and the amount of time spent at work and outside of the home (p>0.05). On analyzing the data collected, it was revealed that the mean of ambient concentrations of Ozone, Nirogen Dioxide and Sulfur Dioxide in case group (sequentially 28.88 ± 14.41PPM, 49.62 ± 19.87PPM and 35.91 ± 20.46 PPM) were significantly higher than control group (sequentially 22.29 ± 7.17 PPM, 45.67 ± 13.2 PPM and 29.1 ± 11.11 PPM) in t test (p<0.001), the odds ratio of spontaneous abortion in the areas with higher concentration of O3 was 0.946 (CI 95% 0.924 - 0.969) and in the areas with higher concentration of NO2 was 0.969 (CI 95% 0.953 – 0.985) (p<0.001). For assessing the relationship between gestational age and environmental O3 and NO2 concentration linear regression technique was used. Results indicated that there was a negative correlation between these variables, also Logestic and Linear Regression model showed that there was no association between prenatal exposure to SO2 and spontaneous abortion. Conclusion: Our results suggest that exposure to ambient O3 and NO2 increase the risk for spontaneous abortion but there was no indication of association between exposure to ambient SO2 and spontaneous abortion. Further research should be directed toward clarifying and quantifying these possible effects and generating testable hypotheses on plausible biologic mechanisms.