A growing body of literature demonstrated an association between exposure to ambient air pollution and maternal health outcomes with mixed findings. The objective of this umbrella review was to systematically summarize the global evidence on the effects of air pollutants on maternal health outcomes. We adopted the Joanna Briggs Institute (JBI) methodology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting standards for this umbrella review. We conducted a comprehensive search across six major electronic databases and other sources to identify relevant systematic reviews and meta-analyses (SRMAs) published from the inception of these databases up to June 30, 2023. Out of 2399 records, 20 citations matched all pre-determined eligibility criteria that include SRMAs focusing on exposure to air pollution and its impact on maternal health, reported quantitative measures or summary effects, and published in peer-reviewed journals in the English language. The risk of bias of included SRMAs was evaluated based on the JBI critical appraisal checklist. All SRMAs reported significant positive associations between ambient air pollution and several maternal health outcomes. Specifically, particulate matter (PM), SO2, and NO demonstrated positive associations with gestational diabetes mellitus (GDM). Moreover, PM and NO2 showed a consistent positive relationship with hypertensive disorder of pregnancy (HDP) and preeclampsia (PE). Although limited, available evidence highlighted a positive correlation between PM and gestational hypertension (GH) and spontaneous abortion (SAB). Only one meta-analysis reported the effects of air pollution on maternal postpartum depression (PPD) where only PM10 showed a significant positive relationship. Limited studies were identified from low- and middle-income countries (LMICs), suggesting evidence gap from the global south. This review necessitates further research on underrepresented regions and communities to strengthen evidence on this critical issue. Lastly, interdisciplinary policymaking and multilevel interventions are needed to alleviate ambient air pollution and associated maternal health disparities.

Background: Gestational diabetes mellitus was associated with increased risks of complications during pregnancy and delivery. The efficacy of probiotics for preventing atopic disease among overweight and obese pregnant women has not been a unified conclusion. Therefore, we aimed to determine the efficacy and safety of probiotics supplementation for overweight and obese pregnant women. Methods: We searched the Cochrane Library, Embase, PubMed, and Web of Science for randomized controlled trials from the earliest publication date available to September 23, 2020, regardless of language or publication status. Two reviewers independently extracted data with a standardized form. When disagreements arose, a third investigator was consulted. Data was pooled using the generic inverse variance method and expressed as mean differences and relative risk with 95% confidence interval (CI). Heterogeneity was measured and quantified by I-2 statistic. Results: There were no significant differences between probiotics and placebo on GDM (RR = 1.03; 95% CI, 0.81-1.30; P = 0.821; I-2 = 38.7%, P = 0.180), excess gestational weight gain (RR = 0.92; 95% CI, 0.79 -1.06; P = 0.223; I-2 = 91.2%, P = 0.001) and neonatal birth weight (WMD = 28.47; 95% CI, -34.80-91.73; P = 0.383; I-2 = 4.5%, P = 0.381). In addition, probiotics might increase the risk of preeclampsia including superimposed (RR = 1.91; 95% CI, 1.03-3.55; P = 0.001; I-2 = 0.0%, P = 0.994). Conclusions: Probiotics had no better efficacy for prevention of atopic disease in overweight or obese pregnant women. In contrast, excessive probiotics supplementation might increase the risk of preeclampsia. More data will be necessary to determine the prevention efficacy of probiotics with consideration of real-world and other epidemiological settings. (C) 2022 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Gestational diabetes mellitus (GDM) is a major public health problem and a threat to maternal and child health. There is a lack of integrated and systematically synthesized knowledge about the prevalence GDM in Norway. Therefore, this systemic review aimed to present the best available peer-reviewed published evidence from the past 20 years about the prevalence of GDM in Norway. A comprehensive literature search was performed on online databases consisting of PubMed (including Medline), Web of Science, and Scopus to retrieve original research articles published on the prevalence of GDM up to August 2020. Also, databases of Norart and SveMed+ in the Norwegian language were searched to enhance the search coverage. Data were extracted using a standardized protocol and data collection form and were presented narratively. A total of 11 studies were selected to include for data analysis and synthesis with the total sample size of 2,314,191 pregnant women. The studies included heterogenous populations and mostly reported the prevalence of GDM in healthy mothers with singleton pregnancies. The prevalence of GDM in population registered-based studies in Norway was reported to be lower than 2%, using the World Health Organization (WHO) 1999 criteria. However, studies on high-risk populations such as the non-European ethnicity reported prevalence rates ranging from 8% to 15%. Given the evidence from available literature that reported trends in the prevalence of GDM, an increase in the prevalence of GDM across most racial/ethnic groups studied in Norway was observed. Overall, the prevalence of GDM in the low risk population of Norway is fairly low, but the available literature supports the perspective that the prevalence of GDM has shown an increasing trend in recent decades. This finding is very important for health service planning and evaluation, policy development, and research in Norway. Large-scale prospective studies, using the national data, are warranted to provide firm evidence over coming years. Our review findings can help policy makers devise appropriate strategies for improving women's reproductive health.