Impact of cash transfers on the association between prenatal exposures to high temperatures and low birthweight: Retrospective analysis from the LEAP 1000 study.

OBJECTIVE: To explore the associations between prenatal temperature exposures and low birthweight (LBW) and modification by cash transfer (CT) receipt. DESIGN: Retrospective cohort study. SETTING: Five rural districts in Northern Ghana. POPULATION OR SAMPLE: A total of 3016 infants born to women interviewed as part of the Livelihood Empowerment Against Poverty (LEAP 1000) impact evaluation between 2015 and 2017. METHODS: Birthweight was collected using household surveys administered to LEAP 1000 eligible women. We used a UNICEF-developed multiple imputation approach to address missingness of birthweight and applied an empirical heaping correction to the multiply imputed birthweight data. Survey data were linked to the European Centre for Medium-Range Weather Forecasts Reanalysis 5-hourly temperature averaged to weeks for 2011-2017 using community centroids. Using distributed-lag nonlinear models, we explored the lag-specific associations between weekly average temperatures greater than 30°C and LBW, and stratified by LEAP 1000 treatment. MAIN OUTCOME MEASURES: Low birthweight (<2.5 kg). RESULTS: Twelve percent (n = 365) of infants were LBW; the mean ± SD birthweight was 3.02 ± 0.37 kg. Overall, increasing temperatures were associated with increased odds of LBW, with the greatest odds observed in the 3 weeks before birth (odds ratio 1.005-1.025). These positive associations were even larger among comparison infants and null among treatment infants. CONCLUSIONS: Our study found increased odds of LBW with high weekly average temperatures throughout pregnancy and the preconception period and demonstrate mitigated effects by the LEAP 1000 CT program. More evidence on the potential of CTs to serve as adaptation interventions in low- and middle-income countries is needed to protect pregnant persons and their infants from the impacts of climate change.

Understanding the physiological and biological response to ambient heat exposure in pregnancy: protocol for a systematic review and meta-analysis.

INTRODUCTION: Climate change increases not only the frequency, intensity and duration of extreme heat events but also annual temperatures globally, resulting in many negative health effects, including harmful effects on pregnancy and pregnancy outcomes. As temperatures continue to increase precipitously, there is a growing need to understand the underlying biological pathways of this association. This systematic review will focus on maternal, placental and fetal changes that occur in pregnancy due to environmental heat stress exposure, in order to identify the evidence-based pathways that play a role in this association. METHODS AND ANALYSIS: We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We will search PubMed and Ovid Embase databases from inception using tested and validated search algorithms. Inclusion of any studies that involve pregnant women and have measured environmental heat stress exposure and either maternal, placental or fetal physiological or biochemical changes and are available in English. Modelling studies or those with only animals will be excluded. The risk of bias will be assessed using the Office of Health Assessment and Translation tool. Abstract screening, data extraction and risk of bias assessment will be conducted by two independent reviewers.Environmental parameters will be reported for each study and where possible these will be combined to calculate a heat stress indicator to allow comparison of exposure between studies. A narrative synthesis will be presented following standard guidelines. Where outcome measures have at least two levels of exposure, we will conduct a dose-response meta-analysis should there be at least three studies with the same outcome. A random effects meta-analysis will be conducted where at least three studies give the same outcome. ETHICS AND DISSEMINATION: This systematic review and meta-analysis does not require ethical approval. Dissemination will be through peer-reviewed journal publication and presentation at international conferences/interest groups. PROSPERO REGISTRATION NUMBER: CRD42024511153.