Environmental heat stress on maternal physiology and fetal blood flow in pregnant subsistence farmers in The Gambia, west Africa: an observational cohort study.

BACKGROUND: Anthropogenic climate change has caused extreme temperatures worldwide, with data showing that sub-Saharan Africa is especially vulnerable to these changes. In sub-Saharan Africa, women comprise 50% of the agricultural workforce, often working throughout pregnancy despite heat exposure increasing the risk of adverse birth outcomes. In this study, we aimed to improve understanding of the pathophysiological mechanisms responsible for the adverse health outcomes resulting from environmental heat stress in pregnant subsistence farmers. We also aimed to provide data to establish whether environmental heat stress also has physiological effects on the fetus. METHODS: We conducted an observational cohort study in West Kiang, The Gambia, at the field station for the Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine (named the MRC Keneba field station). Pregnant women who were aged 16 years or older and who were at <36 weeks' gestation of any gravida or parity were invited to participate in the study. Participants were eligible if they were involved in agricultural or related manual daily tasks of living. Participants were ineligible if they refused to provide consent, had multiple pregnancies (eg, if they had twins), were acutely unwell, or were diagnosed with pre-eclampsia or eclampsia. Heat stress was measured by wet bulb globe temperature (WBGT) and by using the universal thermal climate index (UTCI), and maternal heat strain was directly measured by modified physiological strain index calculated from heart rate and skin temperature. Outcome measures of fetal heart rate (FHR) and fetal strain (defined as a FHR >160 beats per min [bpm] or <115 bpm, or increase in umbilical artery resistance index) were measured at rest and during the working period. Multivariable repeated measure models (linear regression for FHR, and logistic regression for fetal strain) were used to evaluate the association of heat stress and heat strain with acute fetal strain. FINDINGS: Between Aug 26, 2019, and March 27, 2020, 92 eligible participants were recruited to the study. Extreme heat exposure was frequent, with average exposures of WBGT of 27·2°C (SD 3·6°C) and UTCI equivalent temperature of 34·0°C (SD 3·7°C). The total effect of UTCI on fetal strain resulted in an odds ratio (OR) of 1·17 (95% CI 1·09-1·29; p<0·0001), with an adjusted direct effect of OR of 1·12 (1·03-1·21; p=0·010) with each 1°C increase in UTCI. The adjusted OR of maternal heat strain on fetal strain was 1·20 (1·01-1·43; p=0·038), using the UTCI model, with each unit increase. INTERPRETATION: Data from our study show that decreasing maternal exposure to heat stress and heat strain is likely to reduce fetal strain, with the potential to reduce adverse birth outcomes. Further work that explores the association between heat stress and pregnancy outcomes in a variety of settings and populations is urgently needed to develop effective interventions. FUNDING: The Wellcome Trust.

The Challenges of Working in the Heat Whilst Pregnant: Insights From Gambian Women Farmers in the Face of Climate Change.

BACKGROUND: The expected increase in heat in The Gambia is one of the most significant health threats caused by climate change. However, little is known about the gendered dynamics of exposure and response to heat stress, including women's perceived health risks, their adaptation strategies to heat, and their perceptions of climate change. This research project aims to answer the question of whether and how pregnant farmers in The Gambia perceive and act upon occupational heat stress and its health impacts on both themselves and their unborn children, against the backdrop of current and expected climatic changes. METHOD: In-depth semi-structured interviews were conducted with 12 women who practice subsistence farming and were either pregnant or had delivered within the past month in West Kiang, The Gambia. Participants were selected using purposive sampling. Translated interview transcripts were coded and qualitative thematic content analysis with an intersectional lens was used to arrive at the results. RESULTS: All women who participated in the study experience significant heat stress while working outdoors during pregnancy, with symptoms often including headache, dizziness, nausea, and chills. The most common adaptive techniques included resting in the shade while working, completing their work in multiple shorter time increments, taking medicine to reduce symptoms like headache, using water to cool down, and reducing the amount of area they cultivate. Layered identities, experiences, and household power structures related to age, migration, marital situation, socioeconomic status, and supportive social relationships shaped the extent to which women were able to prevent and reduce the effects of heat exposure during their work whilst pregnant. Women who participated in this study demonstrated high awareness of climate change and offered important insights into potential values, priorities, and mechanisms to enable effective adaptation. CONCLUSION: Our findings reveal many intersecting social and economic factors that shape the space within which women can make decisions and take adaptive action to reduce the impact of heat during their pregnancy. To improve the health of pregnant working women exposed to heat, these intersectionalities must be considered when supporting women to adapt their working practices and cope with heat stress.

Impact of Personal Cooling on Performance, Comfort and Heat Strain of Healthcare Workers in PPE, a Study From West Africa.

Background: Personal protective equipment (PPE) is an essential component of safely treating suspected or confirmed SARS-CoV-2 patients. PPE acts as a barrier to heat loss, therefore increasing the risk of thermal strain which may impact on cognitive function. Healthcare workers (HCWs) need to be able to prioritize and execute complex tasks effectively to ensure patient safety. This study evaluated pre-cooling and per-cooling methods on thermal strain, thermal comfort and cognitive function during simulated emergency management of an acutely unwell patient. Methods: This randomized controlled crossover trial was run at the Clinical Services Department of the Medical Research Unit The Gambia. Each participant attended two sessions (Cool and Control) in standard PPE. Cool involved pre-cooling with an ice slurry ingestion and per-cooling by wearing an ice-vest external to PPE. Results: Twelve participants completed both sessions. There was a significant increase in tympanic temperature in Control sessions at both 1 and 2 h in PPE (p = 0.01). No significant increase was seen during Cool. Effect estimate of Cool was -0.2°C (95% CI -0.43; 0.01, p = 0.06) post 1 h and -0.28°C (95% CI -0.57; 0.02, p = 0.06) post 2 h on tympanic temperature. Cool improved thermal comfort (p < 0.001), thermal sensation (p < 0.001), and thirst (p = 0.04). No difference on cognitive function was demonstrated using multilevel modeling. Discussion: Thermal strain in HCWs wearing PPE can be safely reduced using pre- and per-cooling methods external to PPE.