Periconceptional Exposure To Air Pollutants Associated With Birth Defects Study

Objectives: The aim of this study is to investigate the association between the exposures to air pollutions (SO₂, NO₂, and PM₁₀) during maternal pregnant and the risk of birth defects.Methods: Epidemiology Research methods: A population-based case- control study was conducted to analysis the relationship between birth defects and SO₂, NO₂, PM₁₀. The data of birth defects was collected from 20 hospitals in the six districts of Tianjin, an industrial city in the North of China. The data used to be compared was also collected from the same hospitals during the same period (date of birth<30days). The data of the ambient pollutions was offered by Environmental Monitoring Centre of Tianjin. The average density of the air pollutions per month was collected from January 2001 to December 2007 in the six districts of Tianjin. The case–control groups maternal individual level of air pollutions were offered by the related departments of Beijing city. The Latitude and longitude of the every maternal Residence were calculated. First, Epidata software was applied to edit the database of case-control groups from January 2001 to December 2007. Second, the related Confounding factors were removed from the database. 459 Cases and 1080 controls were selected. The date of maternal individual air pollution concentration was input. The complete database was imported into software and corrected.Result: 1 The first six types of the birth defects were: Congenital heart disease (107 cases), Distal limb deformities (90 cases), Ear formation (46 cases) ,Cleft Lip and Palate (43 cases), NTD (37cases)。The mother of case group at being pregnant month was high proportion at months 1, 2, 3, 10, 11, 12. The control group of mothers at the beginning of the pregnant have the opposite trend: the higher ratio happens at 4th, 5th, 7th and 8th month. The month of case group maternal at the beginning of the pregnant which number of heating period constitute ratio was 53.38%; the constituting ratio during the non-heating period was 46.62%. In Control group the constituting ratio during the heating period was 41.11%; the constituting ratio in the number of non-heating period was 58.89%; X2 = 19.60, P = 0.00, the number of case group maternal at pregnant month during the heating period constituting ratio was higher than that of the control group (OR = 1.41, 95% CI 1.21-1.65).2 Statistical analyses of Air pollutants SO₂, NO₂, PM₁₀:2.1 Analysis the balance of three air pollution concentrations distribution among the six districts during the same period from January 2001 to December 2007. There was no significant difference of the SO₂ concentration in the six districts in the same month in addition to January (X2 = 13.00, P = 0.023) and December (X2 = 11.47, P = 0.043). NO₂ concentration in addition to October (X2 = 8.65, P = 0.124), November (X2 = 8.238, P = 0.144), the rest months of NO₂ concentration were significantly different in the administrative regions (P < 0.05). PM₁₀ concentrations in the same period have not significant difference (P > 0.05).2.2 Comparison concentration in the heating period and non-heating period in the years of 2001 - 2007, three kinds of air pollutants whether had difference between of the six areas. SO₂, NO₂ concentration in the heating period was significantly higher than that of non-heating period. PM₁₀ concentration in the year of 2002 (P = 0.337), 2005 (P = 0.055), 2007 (P = 0.201) in the heating and non-heating period have no significant difference. PM₁₀ concentrations during the heating period in the remaining years was higher than that of the non-heating period (all P <0.05).3 Analysis the correlation between Birth defects and the air pollutants (SO₂, NO₂, PM₁₀) concentrations:3.1 Case group maternal in the one month before pregnancy, the 1st month, the 2nd months in early pregnancy and the first trimester of SO₂ concentration was significantly higher than perinatal exposure to maternal corresponding average SO₂ month exposure concentration (t > 0, P < 0.05). Cases group of perinatal maternal pre-pregnancy the first 2 months, 1 month before pregnancy, early pregnancy and 1 month, the beginning of the first 2 month pregnant, 3 months before pregnancy and 3 months in early pregnancy NO₂ exposure was significantly higher than the average of control group, perinatal maternal exposure to the corresponding month of the average concentrations of NO₂ (t > 0, P < 0.05). There was no significant statistical difference of PM₁₀ exposure between case and control groups'mother in the month which is 3 months before pregnancy and during pregnancy.3.2 Chi-square test showed there was no significant difference between case -control groups'maternal Periconceptional period in the heating and non-heating period (X2 = 2.890, P = 0.089, OR = 1.623, CI 95% 0.927 - 2.839).3.3 Correlation analysis between types of birth defects and air pollutants: Compare to the type of birth defects ranked in the top six and control group Perinatal maternal exposed to three kinds of air pollutants. There is positive correlation between the incidence of congenital heart disease and NO₂ pollutants of which Pregnant mother in the 3 months before pregnancy and 3 months in early pregnancy. There was significant difference between limb shortening deformity newborn children maternal in the 3 months before pregnancy and Periconceptional exposure to air pollutants NO₂ with the control groups mothers to the same period. Multi-finger or toe deformities maternal in the 3 months before pregnancy exposure to NO₂ air pollutants with the control group's was significant difference.4 Multivariate analyses of several possible risk factors in the role of the three air pollutants associated with birth defects.To compare maternal pregnant age, gravidity, parity, perinatal fetal gestational age and perinatal weight, 3 months before pregnant and 3 months in the early pregnant of pollutants concentration. The statistically significant factors were: gravidity, perinatal fetal gestational age and the first month NO₂ of pregnant. Gravidity and perinatal fetal gestational age were protective factors .The first month of NO₂ was risk factors. Conclusion: 1 The concentration of SO₂,NO₂ in heating period was higher than that in the non-heating period. 2 Case group concentration of SO₂,NO₂ in 3 months before pregnant and the first trimester was higher than that of the control group. 3 The case group rate of number in heating period was higher than that of control group. 4 Congenital heart diseases, limb shortening, multiple means or toe deformity and the pregnant mother in the 3 months before pregnancy and exposure to NO₂ in the presence of positive correlation. 5 3 months before pregnancy and 3 months in early pregnant were critical periods affecting on birth defects. In those critical periods, pregnant women exposure to high concentrations of air pollutants SO₂, NO₂ will increase the risk of birth defects. 6 The concentration of NO₂ in the month of the beginning of the pregnant will increase the risk of birth defect. The gravidity of women and gestational age were protective factors of birth defect.