Persistent Organic Pollutant exposure as a risk factor of Gestational Diabetes Mellitus: A systematic review and meta-analysis.

Background: The findings of individual epidemiological studies that suggest an association between some Persistent Organic Pollutants (POPs) and Gestational Diabetes Mellitus (GDM) are inconclusive. Objectives: To estimate the strength of the association between POPs exposure and GDM in a systematic review with meta-analysis. Search strategy: MEDLINE, Scopus, and Web of Science were searched until 2022. Selection criteria: Cohort and case-control studies analyzing the association between POPs and GDM in healthy pregnant women. Data collection and analysis: Quality was assessed using QUIPS scale and standardized mean differences (SMD) and 95% confidence intervals (CI) was pooled using random-effect model. Main results: Fourteen articles including 11,422 participants were selected. The risk of bias of included studies was high in 4 (28.6%), moderate in 9 (64.3%) and low in 1 (7.14%). Only six POPs showed a significative SMD between GDM cases and controls: Perfluorobutanesulfonic acid (PFBS) 0.33 (95% CI 0.23, 0.43; I2=0%); Perfluorodecanoic acid (PFDA) -0.11 (95% CI -0.20, -0.01, I2 = 0.0%); 2,2’,3,4,4’,5,5’-Heptachlorobiphenyl (PCB 180) 0.37 (95% CI 0.19, 0.56; I2=25.3%); 2,2’,4,4’,5-Decabromodiphenyl ether (BDE 99) 0.36 (95% CI 0.14, 0.59; I2=0%); 2,2’,4,4’,6-Decabromodiphenyl ether (BDE 100) 0.42 (95% CI 0.19, 0.38; I2=0%); and, Hexachlorobenzene (HCB) 0.22 (95% CI 0.01, 0.42, I2=39.6%). For other POPs, no statistically significant association was observed. Conclusion: The available evidence is variable on quality and results were heterogeneous making impossible to establish a clear association between POPs exposure and risk of GDM. Improve the methodology of epidemiological studies assessing the association of POPs and risk of adverse clinical outcomes are needed.