Replacing biomass fuel with LPG for cooking during pregnancy fails to reduce risk of stunting in infants

In a groundbreaking study spanning four low- and middle-income countries, researchers set out to examine whether a shift from traditional biomass cooking fuels to liquefied petroleum gas (LPG) during pregnancy and early infancy could mitigate the risk of stunting in infants. The study found that the interventional strategy of mitigating household air pollution by replacing biomass fuel with LPG for cooking, starting in pregnancy, did not reduce the risk of stunting in infants.

The study results were published in 'The New England Journal of Medicine.'

Household air pollution, resulting from incomplete combustion of biomass fuels, is a major risk, causing millions of premature deaths and health issues globally. The Household Air Pollution Intervention Network (HAPIN) trial, which explores the shift from biomass to LPG cookstoves, seeks to address critical outcomes, including infant stunting. Hence, William Checkley et al conducted an ongoing trial to provide nuanced insights into the complex interplay between cooking practices, air quality, and health outcomes in vulnerable populations.

Researchers conducted a randomized controlled trial with 3200 pregnant women aged 18 to 34 in four low- and middle-income countries. Women at 9 to less than 20 weeks gestation were randomly assigned to either the intervention group, using a free LPG cookstove with continuous fuel delivery for 18 months, or the control group, continuing with a biomass cookstove. Infant lengths were measured at 12 months, and personal exposures to fine particulate matter were tracked from pregnancy to the infants' first year. The primary outcome presented here is stunting at 12 months, defined as a length-for-age z score more than two standard deviations below the growth standard median. Intention-to-treat analyses were conducted to estimate the relative risk of stunting.

Findings:

• Compliance with the intervention was notable, leading to reduced prenatal and postnatal 24-hour personal exposure to fine particulate matter compared to the control group (average prenatal exposure: 35.0 μg per cubic meter vs. 103.3 μg per cubic meter; average postnatal exposure: 37.9 μg per cubic meter vs. 109.2 μg per cubic meter).
• Among 3061 live births, 76.2% of infants born to intervention group women and 77.8% to control group women had valid 12-month length measurements.
• Despite the success in reducing pollution exposure, the study's primary outcome, stunting at 12 months, did not show a significant difference between the two groups.
• Stunting occurred in 27.4% and 25.2% of infants in the intervention and control groups, respectively.
• The calculated relative risk of stunting was 1.10, with a confidence interval of 0.94 to 1.29, suggesting no statistically significant variance between the groups (P=0.12).