Background: Household air pollution (HAP) is a widespread environmental exposure in low- andmiddle-income countries and may lead to stunted growth in children. We evaluated whether aliquefied petroleum gas (LPG) intervention to mitigate HAP lowered the risk of childhood stunting.Methods: We conducted a randomized controlled trial in four resource-poor settings of Guatemala,India, Peru, and Rwanda where biomass fuels are used as the primary source of energy forcooking. Stunting (length-for-age Z-score two standard deviations below the median of standardpopulation) at age 12 months was one of four primary outcomes. We randomized pregnant womenaged 18-34 years at 9-19 weeks gestation confirmed by ultrasound. Intervention participantsreceived a LPG stove, continuous free fuel delivery and regular behavioral reinforcements for 18months. Controls continued usual cooking practices. We assessed children for linear growth at 12months and monitored personal exposures to PM2.5 and carbon monoxide starting at pregnancythrough the first year of life. We conducted an intention-to-treat analysis adjusted for randomizationstrata to estimate the relative risk (RR) of stunting and the difference in length-for-age Z-score at 12months for intervention children when compared to controls. Given that the trial has four primaryoutcomes, the threshold for statistical significance was set at 0.0125 and thus we present a 98.75%CI for the primary stunting outcome to control the familywise Type I error rate at 0.05. The study wasconducted between May 2018 and September 2021. Results: We randomized 3200 pregnantwomen, and 3061 (96%) children were born alive. Of these, 1171 (76%) and 1186 (78%) had alength measurement at age 12 months, and 320 (27%) and 300 (25%) were stunted in theintervention and control arms, respectively. The COVID-19 pandemic did not affect delivery of theintervention, but some length measurements were missed. Children in the intervention arm had asimilar risk of stunting (RR=1.10, 95% familywise CI 0.97 to 1.24; p=0.15) and similar mean length-for-age Z-score (difference= -0.03 Z-scores, 95% CI -0.11 to 0.05; p=0.45) at age 12 months whencompared to controls. Conclusions: An intervention strategy aimed at mitigating HAP from mid-pregnancy through infancy did not reduce the risk of childhood stunting at one year of age.