Association of air pollution and fine particulate matter (PM2.5) exposure with gestational diabetes: a systematic review and meta-analysis

BACKGROUND: The association between air pollution (AP) and gestational diabetes mellitus (GDM), especially between different pollutants and GDM, remains controversial and debatable. Hence, we conducted this systematic review and meta-analysis to provide comprehensive evidence-based support for the association between AP and GDM. METHODS: The databases of the Cochrane Library, Embase, PubMed, and Web of Science were searched from inception to 1 April 2022, in combination with manual retrieval. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of case-control studies and cohort studies, while the Joana Brigg’s Institute (JBI) critical appraisal checklist was used for the quality assessment of cross-sectional studies. RESULTS: We identified 35 epidemiological studies (including 33 cohort studies, 1 cross-sectional study, and 1 case-control study) covering 6,939,725 pregnant women, of whom 865,460 were GDM patients. The NOS score of all included case-control studies and cohort studies was higher than six, and one of the included cross-sectional studies was rated as high quality according to the JBI assessment. Meta-analysis showed that fine particulate matter and air pollutants [PM2.5, odds ratio (OR) =1.06, 95% confidence interval (CI): 1.05–1.08, Z =7.76, P<0.001; PM10, OR =1.06, 95% CI: 1.01–1.11, Z =2.62, P=0.009; sulfur dioxide (SO(2)), OR =1.18, 95% CI: 1.10–1.26, Z = 4.69, P<0.001; nitric oxide (NO), OR =1.04, 95% CI: 1.03–1.06,Z =3.33, P=0.001; nitrogen oxides (NO(X)), OR =1.07, 95% CI: 1.04–1.11, Z =3.93, P<0.001; black carbon (BC), OR =1.08, 95% CI: 1.06–1.10, Z =7.58, P<0.001] was associated with GDM. Furthermore, no significant association was observed between O(3), CO, and nitrogen dioxide (NO(2)) exposure and GDM. CONCLUSIONS: Exposure to PM2.5, PM10, SO(2), NO, NO(X), and BC significantly increases the risk of GDM. AP is a remediable environmental trigger that can be prevented by human interventions, such as lowering AP levels or limiting human exposure to air pollutants. The government should strengthen the supervision of air quality and make air quality information more transparent. Besides, living conditions are crucial during pregnancy. Living in a place with more green areas is recommended, and indoor air purification should also be enhanced.