Testing a heat early warning system with messages to protect pregnant and postpartum women in Zimbabwe
| ISRCTN | ISRCTN99157575 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN99157575 |
| Sponsor | Centre for Sexual Health and HIV AIDS Research |
| Funders | European Union (EU) – Horizon Europe Programme (Environmental and Health Call), UK Research and Innovation |
- Submission date
- 07/04/2026
- Registration date
- 23/04/2026
- Last edited
- 20/04/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Ongoing
- Condition category
- Pregnancy and Childbirth
Plain English summary of protocol
Background and study aims
Pregnant women, postpartum women, and infants face heightened health risks from extreme heat events exacerbated by climate change, including increased rates of preterm birth and stillbirth, yet existing early warning systems often fail to provide the specific, actionable health guidance required by these vulnerable subpopulations. This study, situated within the broader HIGH Horizons project, aims to evaluate the feasibility, acceptability, and usability of the MotherHeat Alert mobile application in Zimbabwe, a personalised intervention built on the ClimApp platform that translates real-time meteorological data and individual risk factors into tailored heat-health warnings. Specifically, the research seeks to assess the pilot effectiveness of the intervention in improving heat-health knowledge through the delivery of early warning system messaging for maternal adaptation, while also monitoring physiological indicators of hydration, estimating the economic burden of heat exposure, and identifying barriers and facilitators to uptake and sustained use.
Who can participate?
228 pregnant and postpartum women enrolled into the study from across the three study sites, namely Chitse Rural Health Centre, Dotito Rural Health Centre and Mt Darwin District Hospital. To be eligible, participants needed to be at least 16 years old and belong to one of the following groups: pregnant women in their second trimester (16–24 weeks), early postpartum women (infant aged 0–3 months), or late postpartum women (infant aged 6–9 months). Women experiencing serious pregnancy complications requiring hospitalisation were excluded from the study. 35 community health workers from across the three sites were also enrolled to deliver messages to the pregnant and postpartum women.
What does the study involve?
Participants receive personalised heat-health messages through the MotherHeat Alert Early Warning System (EWS). Given limited smartphone access in rural Zimbabwe, delivery is facilitated by trained community health workers (CHWs), referred to as heat champions. Each heat champion is assigned a cohort of 3–10 women and conducts regular home visits to deliver tailored early warning messages and behavioural guidance based on real-time weather data and individual risk factors, including gestational stage. CHWs are equipped with smartphones, solar chargers, and basic cooling kits (an umbrella, a sun hat, a paper fan and a water bottle) to support outreach. Messaging focuses on hydration, thermal regulation, and recognition of danger signs related to dehydration and heat stress. Data are collected at baseline, 3 and 6 months. Quantitative measures include urinary biomarkers of hydration, structured questionnaires assessing heat-health knowledge and economic burden, and basic body measurements. Qualitative data are generated through in-depth interviews and participatory reflection meetings with women and CHWs to assess user experience, acceptability, and implementation fidelity.
What are the possible benefits of participating?
Participants may benefit from receiving timely, personalised heat-health warnings and practical guidance delivered through the MotherHeat Alert Early Warning System, supported by trained community health workers (heat champions). For pregnant and postpartum women, this includes tailored advice on hydration, thermoregulation, workload adjustment, infant care during heat, and early recognition of danger signs such as dehydration in infants and heat-related illness in mothers. While there is no direct therapeutic benefit, the intervention may improve heat-health knowledge and support adaptive practices during pregnancy and the postpartum period. The study is considered low risk and does not involve invasive clinical procedures. Data collection includes basic anthropometric measurements (height and weight), midstream urine sampling to assess hydration, and structured questionnaires. Some participants may experience minor discomfort when discussing personal health, household conditions, or economic circumstances. Participation is entirely voluntary, and participants may withdraw at any time without penalty. In line with the Medical Research Council of Zimbabwe (MRCZ) ethical guidelines, participants receive a reimbursement to cover reasonable costs incurred through participation, including transport and time. This reimbursement is not intended to constitute an inducement to participate. Findings from this study will be used to refine the MotherHeat Alert EWS and its community-based delivery. The results will contribute to evidence on the feasibility and acceptability of early warning system messaging for pregnant and postpartum women in low-resource settings and may inform future scale-up of targeted heat-health interventions.
Where is the study run from?
CeSHHAR Zimbabwe leads the study in collaboration with Mt Darwin District Hospital, Chitse Rural Clinic, and Dotito Rural Clinic (Zimbabwe)
When is the study starting, and how long is it expected to run for?
August 2025 to May 2026
Who is funding the study?
The study is funded by the European Union Horizon Europe Framework Programme as part of the HIGH Horizons project and UK Research and Innovation
Who is the main contact?
Dr Fortunate Machingura, fortunate.machingura@ceshhar.org
Contact information
Public, Principal investigator
10 Coronation Road, Greendale
Harare
263
Zimbabwe
 ORCID ID |
0000-0003-4623-8180 |
|---|---|
| Phone | +263 (0)772971481 |
| fortunate.machingura@ceshhar.org |
Scientific
10 Coronation Road, Greendale
Harare
263
Zimbabwe
| ORCID ID |
0000-0001-5235-5629 |
|---|---|
| Phone | +263 (0)772971481 |
| stanley.luchters@ceshhar.org |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Non-randomized controlled trial |
| Masking | Open (masking not used) |
| Control | Uncontrolled |
| Assignment | Single |
| Purpose | Device feasibility, Health services research, Prevention |
| Scientific title | HIGH Horizons maternal heat early warning system messaging intervention in Zimbabwe: implementation and quasi-experimental evaluation among pregnant and postpartum women |
| Study acronym | MotherHeat Alert EWS |
| Study objectives | Primary objectives: 1. To assess the pilot effectiveness of the MotherHeat Alert early warning system in improving heat-health knowledge among pregnant and postpartum women 2. To evaluate the feasibility, acceptability, and usability of the MotherHeat Alert intervention among pregnant and postpartum women Secondary objectives: 1. To assess physiological responses to heat exposure by measuring changes in hydration status using urinary biomarkers 2. To estimate the economic burden of heat exposure among pregnant and postpartum women and explore the potential for the intervention to mitigate this burden; 3. To explore user experiences and the barriers and facilitators influencing uptake, adherence, and sustained use of the MotherHeat Alert system |
| Ethics approval(s) |
Approved 16/12/2024, Medical Research Council of Zimbabwe (20 Cambridge Road, Avondale, Harare, 263, Zimbabwe; +263 (0)8644 073772; mrcz@mrcz.org.zw), ref: MRCZ A/3109 |
| Health condition(s) or problem(s) studied | Heat-related health risks during pregnancy and the postpartum period |
| Intervention | The MotherHeat Alert Early Warning System (EWS) is a personalised digital health intervention designed to mitigate heat-related risks for pregnant and postpartum women and their newborns in resource-poor settings. The intervention responds to the increasing frequency of extreme heat events associated with climate change, which have been linked to adverse pregnancy outcomes such as preterm birth and stillbirth. The system is built on the ClimApp platform, compatible with Android and iOS devices, and automatically integrates GPS-based local weather forecasts. By year 2 of the HIGH Horizons project, the platform is expected to reach full Technology Readiness Level for the target populations. The EWS integrates multiple environmental and physiological indicators, including air temperature, humidity, wind speed, and solar radiation. It applies advanced human thermal heat-balance models such as Wet-Bulb Globe Temperature (WBGT), the Universal Thermal Climate Index (UTCI), and the ISO7933 Predicted Heat Strain (PHS) model to estimate individual heat stress levels. Risk assessments are further enhanced by incorporating outdoor air pollution data (via OpenWeatherMap API) and self-reported indoor pollution exposure (e.g., biomass fuel use). Unlike conventional EWS approaches, the system translates meteorological data into tailored, actionable health guidance specific to vulnerable subpopulations. Intervention co-design and message development: The intervention adopts a participatory, bottom-up approach to message development. During the formative phase, an adapted Photovoice methodology was used as a citizen science tool. In each study site, groups of pregnant women, postpartum women, and health workers documented lived experiences of heat exposure, coping strategies, and available community resources using cameras or smartphones. Postpartum participants highlighted challenges such as maintaining breastfeeding during extreme heat. Through iterative analysis involving participants, community health workers (CHWs), and other stakeholders and with oversight from a WHO expert group, key themes were identified and translated into culturally relevant messages delivered as text and infographics. Eight core behavioural themes informed the intervention: 1. Directly cool the body 2. Plan ahead 3. Stay in cool environments 4. Avoid or limit sun exposure 5. Take care of yourself 6. Utilise support services 7. Adjust clothing 8. Stay hydrated 9. Personalisation and risk stratification A defining feature of the MotherHeat Alert system is its high level of personalisation. Messages are tailored based on individual physiological status and weighted risk factors, such as multiple pregnancies or infant prematurity. Distinct message sets are developed for: 1. Pregnant women (16–24 weeks of gestation) 2. Early postpartum women (infants 0–3 months) 3. Late postpartum women (infants 6–9 months) This ensures that guidance on hydration, infant care, sun exposure, and heat avoidance is relevant to each participant’s circumstances. Delivery Mechanism and Community Engagement Due to limited smartphone ownership, internet connectivity, and electricity access in rural Zimbabwe, the intervention uses CHWs (heat champions) as the primary delivery mechanism. A total of 35 heat champions were recruited and equipped with smartphones, solar-powered chargers, and personal cooling kits (umbrella, hat, paper fan, water bottle). Each Heat Champion supports 3-10 women and delivers personalised alerts and advice through weekly home visits. Heat champions: 1. Receive alerts via the mobile application 2. Deliver warnings at least three days before extreme heat events 3. Provide weekly in-person guidance and support 4. The system also supports proactive, non-alert messaging focused on preparedness, hydration practices, and recognition of maternal and infant danger signs. Procedural activities: The participants are given a tailored intervention package that is implemented for a period of 6 months. During this period, the participants are visited once a week at home by community health workers who give them tailored messages for hydration and adaptation to heat. Data is collected using surveys at baseline, midline (after 3 months), and endline (after 6 months). Participants also receive additional alerts before extreme heat waves to boost their protective responses. Urine samples are also collected during the study period to measure participants’ urine specific gravity and osmolality. Some participants also take part in in-depth interviews and reflection sessions. Setting and Implementation: The intervention is implemented in the Mt Darwin District of Zimbabwe across three health facility catchment areas: 1. Mt Darwin District Hospital (peri-urban) 2. Dotito Rural Health Centre (rural) 3. Chitse Rural Health Centre (rural) The intervention design is adapted from a direct-to-user mobile model to a CHW-supported model to address contextual barriers, including low smartphone penetration, limited electricity access, and high data costs. Implementation monitoring: Fidelity of intervention delivery: Implementation fidelity was monitored to assess whether the MotherHeat Alert Early Warning System (EWS) was delivered as intended. Key fidelity indicators included: (i) the proportion of scheduled home visits completed by heat champions; (ii) timely delivery of early warning messages (≥3 days before forecasted heat events); and (iii) consistency of message delivery with the co-designed messaging package. Fidelity monitoring combined multiple data sources, including real-time WhatsApp reporting by heat champions, app-based interaction data, and participant-reported experiences. Additional assessment was conducted through surveys, in-depth interviews, and participatory reflection meetings with pregnant and postpartum women, heat champions, and household members. Urinary biomarkers (specific gravity and osmolality) were used as objective indicators of behavioural response to heat-health messaging. Dose delivered: Dose delivered refers to the amount of intervention provided. Over the six-month implementation period, heat champions conducted weekly home visits to deliver tailored heat-health messages and behavioural guidance. In addition, early warning alerts were issued ahead of extreme heat events to support anticipatory action. Evaluation activities, including baseline, midline (3 months), and endline (6 months) assessments, as well as periodic urine sampling, were integrated into the intervention schedule. Dose received: Dose received reflects participant engagement with, and response to, the intervention. Messages were tailored to the pregnancy or postpartum stage and aligned with core behavioural domains addressing hydration, cooling, reduced heat exposure, and maternal and infant care. Engagement was assessed through self-reported knowledge, behavioural adaptation, and perceived usefulness of messages, captured via structured questionnaires and qualitative methods. In-depth interviews and participatory reflection meetings further explored comprehension, acceptability, and contextual barriers to applying recommended practices. Reach and coverage: The intervention was implemented across three health facility catchment areas in Mt Darwin District (Mt Darwin District Hospital, Dotito, and Chitse), enrolling 228 pregnant and postpartum women followed over six months. Reach was achieved through a community-based delivery model, with 35 trained Heat Champions each supporting 3–10 women. This approach enabled the delivery of early warning messages and behavioural guidance in settings with limited access to smartphones, internet connectivity, and electricity, thereby extending access to interventions for and peri-urban populations. |
| Intervention type | Behavioural |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 18/05/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 16 Years |
| Upper age limit | 49 Years |
| Sex | Female |
| Target sample size at registration | 200 |
| Total final enrolment | 228 |
| Key inclusion criteria | 1. Pregnant/postpartum women 2. Aged 16 years or older 3. Confirmed pregnancy in the 2nd trimester (16-24 weeks) or having an infant aged 0–3 months and 6-9 months 4. Resident in the Mt Darwin District for at least 6 months 5. Able and willing to provide informed consent |
| Key exclusion criteria | 1. Experiencing severe or unstable medical or obstetric conditions requiring hospitalisation or intensive clinical management at the time of recruitment 2. Unable to participate in study procedures due to serious illness or clinical instability 3. Not intending to remain in the study area for the duration of follow-up 4. Unable or unwilling to provide informed consent |
| Date of first enrolment | 13/08/2025 |
| Date of final enrolment | 13/04/2026 |
Locations
Countries of recruitment
- Zimbabwe
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Not expected to be made available |
| IPD sharing plan |
Editorial Notes
08/04/2026: Study's existence confirmed by the Medical Research Council of Zimbabwe.
