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other·epidemiology, public health, environmental health, obstetrics, pediatrics·PMC10186177

Exposure–response relationships for personal exposure to fine particulate matter (PM 2·5 ), carbon monoxide, and black carbon and birthweight: an observational analysis of the multicountry Household Air Pollution Intervention Network (HAPIN) trial

The Lancet. Planetary Health · 36 authors, 18 centres

AI SUMMARY

FIDELITY 97%

POPULATIONPregnant women (9–<20 weeks gestation) aged 18–35 years, non-smoking, using biomass as primary fuel, from rural Guatemala, India, Peru, and Rwanda (n=3200 enrolled, 3002 included in analysis)

INTERVENTIONMeasured 24-hour personal exposures to PM2.5, black carbon, and carbon monoxide during pregnancy (baseline, 24–28 weeks, 32–36 weeks gestation)

COMPARISONHigher versus lower exposure levels (continuous exposure metrics; also compared intervention group receiving LPG stove vs control group continuing biomass, but this is an exposure-response analysis)

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

TRACE TO SOURCE

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TL;DR

This multicountry analysis found that higher prenatal exposure to PM2.5 and black carbon from household air pollution was associated with lower birthweight and weight-for-gestational-age Z-scores, while carbon monoxide showed no association. An interquartile increase in PM2.5 (74.5 μg/m³) was linked to a 14.8 g reduction in birthweight, and a similar increase in black carbon (7.3 μg/m³) to a 21.9 g reduction. These findings support continued efforts to reduce household air pollution alongside other risk factors for low birthweight in low- and middle-income countries.

Full summary

3,258 CHARS

**Background:** Household air pollution (HAP) from solid fuel use is a major health risk in low- and middle-income countries (LMICs), but quantitative exposure-response data for birth outcomes are scarce. This study aimed to characterize associations between prenatal personal exposures to PM2.5, black carbon (BC), and carbon monoxide (CO) and birthweight, using data from the multicountry Household Air Pollution Intervention Network (HAPIN) trial.

**Methods:** The HAPIN trial enrolled 3200 pregnant women (9–<20 weeks gestation) in rural Guatemala, India, Peru, and Rwanda, randomly allocating them to receive a liquefied petroleum gas (LPG) stove or continue using biomass. For this exposure-response subanalysis, 24-hour personal exposures to PM2.5 (gravimetric and nephelometric), BC (optical transmission), and CO (data logger) were measured once pre-intervention (baseline) and twice post-intervention (24–28 and 32–36 weeks). Birthweight was measured within 24 hours of birth using a digital scale. Gestational age was determined by ultrasound. Weight-for-gestational-age Z-scores were derived using INTERGROWTH standards. Multivariate linear regression models were used, adjusting for mother's age, nulliparity, diet diversity, food insecurity, BMI, education, neonate sex, hemoglobin, second-hand smoke, and randomization strata. Non-linear models (quadratic, spline, generalized additive) were also evaluated. Analyses were conducted separately for each pollutant.

**Key Results:** Of 3195 pregnancies, 3060 resulted in live births, and 3002 had valid birthweights and gestational age <300 days. Mean birthweight was 2909 g (SD 471); 17.7% were low birthweight (<2500 g). Mean weighted prenatal exposures were: PM2.5 92.2 μg/m³ (SD 83.9), BC 10.0 μg/m³ (7.4), CO 2.0 ppm (2.9). An interquartile range (IQR) increase in PM2.5 (74.5 μg/m³) was associated with a reduction in birthweight of –14.8 g (95% CI –28.7 to –0.8) and in Z-score of –0.03 (95% CI –0.06 to 0.00). For BC (IQR 7.3 μg/m³), the reductions were –21.9 g (95% CI –37.7 to –6.1) and –0.05 (95% CI –0.08 to –0.01). CO (IQR 1.7 ppm) showed no significant association: –3.1 g (95% CI –12.1 to 5.8) and –0.003 (95% CI –0.023 to 0.017). Non-linear models for PM2.5 suggested a quadratic relationship with birthweight (initial increase then decrease at higher exposures). Results were consistent across countries and for full-term births. No significant interaction by neonate sex was found, though effects appeared larger in females.

**Clinical Implications:** This study provides novel exposure-response estimates for HAP pollutants and birthweight, including the first for black carbon. The modest but significant associations (e.g., ~22 g lower birthweight per IQR increase in BC) suggest that reducing HAP exposure could yield population-level benefits for birthweight, potentially reducing infant mortality. The findings support continued efforts to reduce HAP alongside other risk factors for low birthweight in LMICs. The lack of association with CO may reflect weak correlations with PM2.5/BC in this setting. Limitations include potential unmeasured confounders (e.g., placental malaria, nutrition) and exposure measurement error, which likely biases results toward the null.

PICO

PPOPULATION

Pregnant women (9–<20 weeks gestation) aged 18–35 years, non-smoking, using biomass as primary fuel, from rural Guatemala, India, Peru, and Rwanda (n=3200 enrolled, 3002 included in analysis)

IINTERVENTION

Measured 24-hour personal exposures to PM2.5, black carbon, and carbon monoxide during pregnancy (baseline, 24–28 weeks, 32–36 weeks gestation)

OOUTCOME

Birthweight (g) and weight-for-gestational-age Z-scores (INTERGROWTH standards)

STUDY TYPE

other

SPECIALTY

epidemiology

SUMMARISED BY

AI pipeline

FIDELITY CHECK

97% · A

ORIGINAL PAPER

PMC10186177

Exposure–response relationships for personal exposure to fine particulate matter (PM 2·5 ), carbon monoxide, and black carbon and birthweight: an observational analysis of the multicountry Household Air Pollution Intervention Network (HAPIN) trial

The Lancet. Planetary Health

READ THE FULL PAPER

ABSTRACT

Summary Background Household air pollution (HAP) from solid fuel use is associated with adverse birth outcomes, but data for exposure–response relationships are scarce. 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 The HAPIN trial recruited pregnant women (9–<20 weeks of gestation) in rural Guatemala, India, Peru, and Rwanda and randomly allocated them to receive a liquefied petroleum gas stove or not (ie, and continue to use biomass fuel). The primary outcomes were birthweight, length-for-age, severe pneumonia, and maternal systolic blood pressure. In this exposure–response subanalysis, we measured 24-h personal exposures to PM 2·5 , carbon monoxide, and black carbon once pre-intervention (baseline) and twice post-intervention (at 24–28 weeks and 32–36 weeks of gestation), as well as birthweight within 24 h of birth. We examined the relationship between the average prenatal exposure and birthweight or weight-for-gestational age Z scores using multivariate-regression models, controlling for the mother's age, nulliparity, diet diversity, food insecurity, BMI, the mother's education, neonate sex, haemoglobin, second-hand smoke, and geographical indicator for randomisation strata. Findings Between March, 2018, and February, 2020, 3200 pregnant women were recruited. An interquartile increase in the average prenatal exposure to PM 2·5 (74·5 μg/m 3 ) was associated with a reduction in birthweight and gestational age Z scores (birthweight: –14·8 g [95% CI –28·7 to –0·8]; gestational age Z scores: –0·03 [–0·06 to 0·00]), as was an interquartile increase in black carbon (7·3 μg/m 3 ; –21·9 g [–37·7 to –6·1]; –0·05 [–0·08 to –0·01]). Carbon monoxide exposure was not associated with these outcomes (1·7; –3·1 [–12·1 to 5·8]; –0·003 [–0·023 to 0·017]). Interpretation Continuing efforts are needed to reduce HAP exposure alongside other drivers of low birthweight in low-income and middle-income countries. Funding US National Institutes of Health (1UM1HL134590) and the Bill & Melinda Gates Foundation (OPP1131279).

CITATION EXPORT

Kalpana Balakrishnan, Kyle Steenland, Thomas Clasen et al.. Exposure–response relationships for personal exposure to fine particulate matter (PM2·5), carbon monoxide, and black carbon and birthweight: an observational analysis of the multicountry Household Air Pollution Intervention Network (HAPIN) trial. The Lancet. Planetary Health. (2023). https://doi.org/10.1016/S2542-5196(23)00052-9

AUTHORS

36 · 18 CENTRES

Kalpana Balakrishnan, Kyle Steenland, Thomas Clasen, Howard Chang, Michael Johnson, Ajay Pillarisetti, Wenlu Ye, Luke P Naeher, Anaite Diaz-Artiga, John P McCracken, Lisa M Thompson, Ghislaine Rosa, Miles A Kirby, Gurusamy Thangavel, Sankar Sambandam, Krishnendu Mukhopadhyay, Naveen Puttaswamy, Vigneswari Aravindalochanan, Sarada Garg, Florien Ndagijimana, Stella Hartinger, Lindsay J Underhill, Katherine A Kearns, Devan Campbell, Jacob Kremer, Lance Waller, Shirin Jabbarzadeh, Jiantong Wang, Yunyun Chen, Joshua Rosenthal, Ashlinn Quinn, Aris T Papageorghiou, Usha Ramakrishnan, Penelope P Howards, William Checkley, Jennifer L Peel

aDepartment of Environmental Health Engineering, ICMR Center for Advanced Research on Air Quality, Climate and Health, Sri Ramachandra Institute for Higher Education and Research (Deemed University), Chennai, India
bGangarosa Department of Environmental Health, Emory University, Atlanta, GA, USA
cDepartment of Biostatistics and Bioinformatics, Emory University, Atlanta, GA, USA
dHubert Department of Global Health, Emory University, Atlanta, GA, USA
eDepartment of Epidemiology, Emory University, Atlanta, GA, USA
fRollins School of Public Health and Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA, USA
gBerkeley Air Monitoring Group, Berkeley, CA, USA
hDivision of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA
iDepartment of Environmental Health Sciences, University of Georgia, Athens, GA, USA
jCenter for Health Studies, Universidad del Valle de Guatemala, Guatemala City, Guatemala
kDepartment of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
lDepartment of Global Health and Population, Harvard T H Chan School of Public Health, Harvard University, Boston, MA, USA
mEagle Research Centre, Kigali, Rwanda
nDivision of Pulmonary and Critical Care, School of Medicine and Center for Global Non-Communicable Disease Research and Training, Johns Hopkins University, Baltimore, MD, USA
oCardiovascular Division, Washington University School of Medicine, St Louis, MO, USA
pDivision of Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
qNuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, UK
rDepartment of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA