Health outcome · disease
Small for gestational age (SGA)
Part of: Birth outcomes
Also: SGA, small-for-gestational-age, fetal growth restriction, intrauterine growth restriction
A birth weight below the tenth percentile for the length of the pregnancy, in a reference population. Unlike low birth weight, it separates growth from prematurity: the baby is small for the time it had, not merely small.
Not reviewed by a clinician. This entry describes a disease or a symptom. We are introducing clinical review for pages of this kind; until that reviewer is in place, this page has been written and checked by the Coridum team but not reviewed by a clinician. It is general information and not medical advice. How this library is built is described in How we build this library.
Why it matters indoors
The value of this outcome in indoor air research is that it isolates one mechanism. If an exposure acts by shortening the pregnancy, it shows in preterm birth; if it acts by slowing growth in the womb, it shows here. Low birth weight mixes the two and cannot tell them apart.
The mechanism proposed for combustion exposures is a growth mechanism. Carbon monoxide binds haemoglobin and reduces the oxygen the placenta can deliver; fine particles provoke inflammation and affect placental vessel function. Both would restrict growth without necessarily triggering early labour, which is the pattern several household studies report.
Two cautions belong with the figure. It is defined against a reference population, so the same baby can be classified differently under different references; and a birth that is both early and growth-restricted appears in both categories, which is why studies report them separately rather than adding them.
Indoor factors with evidence
| Factor | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Particulate matter (PM₂.₅ and PM₁₀) | difference 96 | pregnant women | hospital-based multicentre prospective cohort (APPO study) of 662 pregnant women in Korea with individual PM10 and PM2.5 exposure estimated from time-activity patterns and indoor and outdoor concentrations, logistic regression adjusted for maternal age, pre-pregnancy BMI, sex of the baby, income and education | F-0175 Association Between Individual Air Pollution (PM10, PM2.5) E… (2024) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | difference 26 | pregnant women | hospital-based multicentre prospective cohort (APPO study) of 662 pregnant women in Korea with individual PM10 and PM2.5 exposure estimated from time-activity patterns and indoor and outdoor concentrations, logistic regression adjusted for maternal age, pre-pregnancy BMI, sex of the baby, income and education | F-0176 Association Between Individual Air Pollution (PM10, PM2.5) E… (2024) | machine |
| Ozone (O₃) | RR 1.037 (1.026–1.048) 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-1295 Gestational Hypertension as a Mediator of Prenatal Ozone Exp… (2026) | machine |
| Biomass fuel | OR 1.87 (1.03–3.41) | — · 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-1696 Vakalopoulos et al. Household Air Pollution from Biomass Fuel for Cooking and Ad… (2021) | machine |
| Air purifiers | OR 0.94 (0.89–1.00) | — · 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-1671 Inadera Association of air purifier usage during pregnancy with adve… (2024) | 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. Small for gestational age (SGA). Coridum Knowledge G-0148, 16 September 2026. https://coridum.com/k/G-0148/