Exposure–response relationships for personal exposure to fine particulate matter (PM2·5), carbon monoxide, and black carbon and birthweight: Results from the multi-country Household Air Pollution Intervention Network (HAPIN) trial

Background Household air pollution (HAP) from solid fuel use is associated with adverse birth outcomes, but data on exposure-response relationships are limited. We examined associations between HAP exposures and birthweight in rural Guatemala, India, Peru, and Rwanda during the Household Air Pollution Intervention Network (HAPIN) trial. Methods We recruited 3200 pregnant women between 9 and <20 weeks of gestation. Women randomized to the intervention arm received a liquified petroleum gas (LPG) stove and fuel during pregnancy, while control arm women continued using biomass. We measured 24-hr personal exposures to particulate matter (PM2·5), carbon monoxide (CO), and black carbon (BC) once pre-intervention (baseline), twice post-intervention, and birthweight within 24 hours of birth. We examined the relationship between the average prenatal exposure and birthweight/weight-for-gestational age z-scores using multivariate-regression models. Findings Results showed an inter-quartile increase in average prenatal exposure to PM2.5 (74·5 μg/m3) and BC (7·3 μg/m3) was associated with a 14·8 (95% confidence interval [CI]: -28·7g, - 0·8g) and 21·9g (95% CI: -37·3g, -6·1g) reduction in birthweight and reduced weight-for-gestational age z-scores of -0·03 (95% CI: -0.06, 0·00) and -0·05 (95%CI: -0·08, -0·01) standard deviations, respectively. We found no associations for birthweight or weight-for-gestational age z-scores with CO exposures. Interpretation Results provide support for continuing efforts to reduce HAP exposure alongside other drivers of low birthweight in low- and middle-income countries. Funding The study is registered with [ClinicalTrials.gov][1] ([NCT02944682][2]) and funded by the U.S. National Institutes of Health (1UM1HL134590) in collaboration with the Bill & Melinda Gates Foundation (OPP1131279). ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT02944682 ### Clinical Protocols ### Funding Statement The HAPIN trial is funded by the U.S.National Institutes of Health (cooperative agreement UM1HL134590) in collaboration with the Bill & Melinda Gates Foundation (OPP1131279). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocol was reviewed and approved by institutional review boards (IRBs) or Ethics Committees at Emory University (00089799), Johns Hopkins University (00007403), Sri Ramachandra Institute of Higher Education and Research (IEC-N1/16/JUL/54/49) and the Indian Council of Medical Research, Health Ministry Screening Committee (5/8/4-30/(Env)/Indo-US/2016-NCD-I), Universidad del Valle de Guatemala (146-08-2016/11-2016) and Guatemalan Ministry of Health National Ethics Committee (11-2016), A.B. PRISMA, the London School of Hygiene and Tropical Medicine (11664-5) and the Rwandan National Ethics Committee (No.357/RNEC/2018), and Washington University in St. Louis (201611159) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors [1]: http://ClinicalTrials.gov [2]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT02944682&atom=%2Fmedrxiv%2Fearly%2F2022%2F08%2F08%2F2022.08.06.22278373.atom