Preconception air pollution exposure and glucose tolerance in healthy pregnant women in a middle-income country

BACKGROUND: Preconception exposure to air pollution has been associated with glucose tolerance during pregnancy. However, the evidence in low and middle-income countries (LMICs) is under debate yet. Therefore, this study aimed to assess the relationship between exposure to ambient particulate matter (PM) and traffic indicators with glucose tolerance in healthy pregnant women in Sabzevar, Iran (2019). METHODS: Two-hundred and fifty healthy pregnant women with singleton pregnancies and 24–26 weeks of gestations participated in our study. Land use regression (LUR) models were applied to estimate the annual mean of PM(1), PM(2.5) and PM(10) at the residential address. Traffic indicators, including proximity of women to major roads as well as total streets length in 100, 300 and 500 m buffers around the home were calculated using the street map of Sabzevar. The oral glucose tolerance test (OGTT) was used to assess glucose tolerance during pregnancy. Multiple linear regression adjusted for relevant covariates was used to estimate the association of fasting blood glucose (FBG), 1-h and 2-h post-load glucose with PMs and traffic indicators. RESULTS: Exposure to PM(1), PM(2.5) and PM(10) was significantly associated with higher FBG concentration. Higher total streets length in a 100 m buffer was associated with higher FBG and 1-h glucose concentrations. An interquartile range (IQR) increase in proximity to major roads was associated with a decrease of − 3.29 mg/dL (95% confidence interval (CI): − 4.35, − 2.23, P-value < 0.01) in FBG level and − 3.65 mg/dL (95% CI, − 7.01, − 0.28, P-value = 0.03) decrease in 1-h post-load glucose. CONCLUSION: We found that higher preconception exposure to air pollution was associated with higher FBG and 1-h glucose concentrations during pregnancy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12940-020-00682-y.