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Nyadanu SD, Dunne J, Tessema GA, Mullins B, Kumi-Boateng B, Bell ML, Duko B, Pereira G. Maternal exposure to ambient air temperature and adverse birth outcomes: An umbrella review of systematic reviews and meta-analyses. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170236. [PMID: 38272077 DOI: 10.1016/j.scitotenv.2024.170236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 12/28/2023] [Accepted: 01/15/2024] [Indexed: 01/27/2024]
Abstract
BACKGROUND Multiple systematic reviews on prenatal ambient temperature and adverse birth outcomes exist, but the overall epidemiological evidence and the appropriate metric for thermal stress remain unclear. An umbrella review was performed to summarise and appraise the evidence with recommendations. METHODS Systematic reviews and meta-analyses on the associations between ambient temperature and adverse birth outcomes (preterm birth, stillbirth, birth weight, low birth weight, and small for gestational age) up to December 20, 2023, were synthesised according to a published protocol. Databases PubMed, CINAHL, Scopus, MEDLINE/Ovid, EMBASE/Ovid, Web of Science Core Collection, systematic reviews repositories, electronic grey literature, and references were searched. Risk of bias was assessed using Joanna Briggs Institute's critical appraisal tool. RESULTS Eleven systematic reviews, including two meta-analyses, were included. This comprised 90 distinct observational studies that employed multiple temperature assessment metrics with a very high overlap of primary studies. Primary studies were mostly from the United States while both Africa and South Asia contributed only three studies. A majority (7 out of 11) of the systematic reviews were rated as moderate risk of bias. All systematic reviews indicated that maternal exposures to both extremely high and low temperatures, particularly during late gestation are associated with increased risks of preterm birth, stillbirth, and reduced fetal growth. However, due to great differences in the exposure assessments, high heterogeneity, imprecision, and methodological limitations of the included systematic reviews, the overall epidemiological evidence was classified as probable evidence of causation. No study assessed biothermal metrics for thermal stress. CONCLUSIONS Despite the notable methodological differences, prenatal exposure to extreme ambient temperatures, particularly during late pregnancy, was associated with adverse birth outcomes. Adhering to the appropriate systematic review guidelines for environmental health research, incorporating biothermal metrics into exposure assessment, evidence from broader geodemographic settings, and interventions are recommended in future studies.
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Affiliation(s)
- Sylvester Dodzi Nyadanu
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia; Education, Culture, and Health Opportunities (ECHO) Ghana, ECHO Research Group International, P. O. Box 424, Aflao, Ghana.
| | - Jennifer Dunne
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia
| | - Gizachew A Tessema
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia; School of Public Health, University of Adelaide, Adelaide, South Australia 5000, Australia
| | - Ben Mullins
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia
| | - Bernard Kumi-Boateng
- Department of Geomatic Engineering, University of Mines and Technology, P. O. Box 237, Tarkwa, Ghana
| | - Michelle L Bell
- School of the Environment, Yale University, New Haven, CT 06511, USA
| | - Bereket Duko
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia
| | - Gavin Pereira
- Curtin School of Population Health, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia; enAble Institute, Curtin University, Perth, Kent Street, Bentley, Western Australia 6102, Australia; WHO Collaborating Centre for Climate Change and Health Impact Assessment, Faculty of Health Science, Curtin University, WA, Australia
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Bias in the association between advanced maternal age and stillbirth using left truncated data. Sci Rep 2022; 12:19214. [PMID: 36357770 PMCID: PMC9649623 DOI: 10.1038/s41598-022-23719-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/03/2022] [Indexed: 11/12/2022] Open
Abstract
Restriction to analysis of births that survive past a specified gestational age (typically 20 weeks gestation) leads to biased exposure-outcome associations. This bias occurs when the cause of restriction (early pregnancy loss) is influenced by both the exposure and unmeasured factors that also affect the outcome. The aim of this study is to estimate the magnitude of bias resulting from left truncated data in the association between advanced maternal age and stillbirth. We simulated data for the causal pathway under a collider-stratification mechanism. Simulation parameters were based on an observed birth cohort from Western Australia and a range of plausible values for the prevalence of early pregnancy loss, unmeasured factor U and the odds ratios for the selection effects. Selection effects included the effects of maternal age on early pregnancy loss, U on early pregnancy loss, and U on stillbirth. We compared the simulation scenarios to the observed birth cohort that was truncated to pregnancies that survived beyond 20 gestational weeks. We found evidence of marginal downward bias, which was most prominent for women aged 40 + years. Overall, we conclude that the magnitude of bias due to left truncation is minimal in the association between advanced maternal age and stillbirth.
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