Health outcome · disease
Low birth weight
Part of: Birth outcomes
Also: LBW, low birthweight, birth weight below 2500 g
A birth weight below 2500 g, whatever the cause. It combines two different problems — a baby born too early and a baby born too small for its age — which is why it is easy to measure everywhere and harder to interpret than either of them alone.
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Why it matters indoors
Low birth weight is the birth outcome recorded most consistently across the world, because it needs only a scale, and that is both its strength and its weakness in this literature. Every registry has it, so associations with household exposures can be looked for almost anywhere; but a baby can fall below the threshold by arriving early, by growing slowly, or by both, and the exposure may act on only one of those paths.
Where studies separate them — reporting preterm birth and small for gestational age as well — the separate results are the more informative ones, and Coridum records them under their own slugs.
The exposures implicated indoors are those of combustion: cooking on solid fuel during pregnancy, and tobacco smoke, whose effect on birth weight is among the oldest established findings in the field.
Indoor factors with evidence
| Factor | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Tobacco smoke (secondhand smoke) | OR 2.63 (1.09–6.35) | pregnant women and their newborns · home | systematic review and meta-analysis of environmental exposures and adverse pregnancy outcomes in Ethiopia: seven eligible studies on active and passive cigarette smoking and low birth weight, pooled with a random effects model and checked with a sensitivity analysis | F-1347 Enyew et al. Environmental exposures and adverse pregnancy outcomes in Et… (2023) | machine |
| Wood | OR 0.74 (0.33–1.66) · borderline | pregnant women and their newborns · home | analysis inside RESPIRE, a randomised trial in rural Guatemala: pregnant women were given a chimney stove or kept an open fire, with 48-hour personal carbon monoxide measured in pregnancy and newborn birth weight measured within 48 hours of birth, adjusted for maternal height, gravidity, blood pressure and season | F-0979 Impact of Reduced Maternal Exposures to Wood Smoke from an I… (2011) | machine |
| Ozone (O₃) | RR 1.055 (1.034–1.077) per 1 | pregnant women and their term births · city (ambient) | cohort of 113,382 births in Shandong Province, China, between 2016 and 2022: ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide and temperature during pregnancy estimated at the mother's address and related to term low birth weight and small for gestational age with logistic regression, Cox proportional hazards models and a mediation analysis through gestational hypertension | F-1294 Gestational Hypertension as a Mediator of Prenatal Ozone Exp… (2026) | machine |
| Biomass fuel | OR 2.74 (1.08–6.96) | — · home | cohort study of pregnant women: the household cooking fuel related to low birth weight and small-for-gestational-age, adjusted for confounders, with the stove type and the kitchen arrangement examined separately | F-1695 Vakalopoulos et al. Household Air Pollution from Biomass Fuel for Cooking and Ad… (2021) | machine |
| Tobacco smoke (secondhand smoke) | prevalence 16.0 | mothers and their most recent births · home | analysis of Demographic and Health Survey data from sub-Saharan Africa: household second-hand smoke reported by the mother, against the birth weight and the perceived size at birth of her most recent child | F-1332 Yaya Association between household second-hand smoke and low birt… (2025) | machine |
| Air purifiers | OR 0.89 (0.85–0.93) | — · home | cohort study of air purifier use during pregnancy: preterm birth, small-for-gestational-age and low birth weight compared between the mothers who used an air purifier and those who did not, in a crude and in an adjusted model | F-1672 Inadera Association of air purifier usage during pregnancy with adve… (2024) | machine |
| Biomass fuel | OR 1.7 (1.3–2.3) | — · home | analysis of the Ethiopia Demographic and Health Survey: cooking fuel of the household recorded by interview and birth weight of the infant recorded, with crude and adjusted odds ratios for low birth weight | F-1792 Kanno Effect of biomass fuel use and kitchen location on maternal … (2021) | machine |
| Biomass fuel | prevalence 26.2 | — · home | analysis of the Ethiopia Demographic and Health Survey: cooking fuel of the household recorded by interview and birth weight of the infant recorded, with crude and adjusted odds ratios for low birth weight | F-1793 Kanno Effect of biomass fuel use and kitchen location on maternal … (2021) | machine |
Each row is one Finding — a sentence as printed in one study, recorded with its page in the Coridum Knowledge Base. Follow the Finding number for the exact wording and the citation. Checked says who verified the row: machine means every automatic check passed and the surrounding text was read; person means someone read the sentence in the document. Rows are re-checked by a person over time. The studies are curated in the Coridum Knowledge Base; the reading of them together is a Claim, shown separately.
Cite this page
Coridum Research. Low birth weight. Coridum Knowledge G-0145, 16 September 2026. https://coridum.com/k/G-0145/