Health outcome · disease
Preterm birth
Part of: Birth outcomes
Also: PTB, premature birth, prematurity, preterm delivery
Birth before 37 completed weeks of gestation. It is the birth outcome with the clearest definition and the gravest consequences, and the one in which an environmental exposure would have to act on the timing of labour rather than on growth.
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Why it matters indoors
Gestational age is recorded, so this outcome needs no threshold on a scale and no reference population: a birth is preterm or it is not. That makes it the cleanest of the birth outcomes to study and the one where results across settings can most fairly be compared.
The mechanism would have to be different from the one proposed for growth restriction. Labour beginning early is associated with inflammation and with infection, which is the route through which particle exposure is thought to act here — not through oxygen delivery, which is the argument for small for gestational age.
Indoor evidence comes from two directions: cohorts comparing households by cooking fuel, and the rarer and more valuable trials in which air was cleaned during pregnancy. Results from the latter have been mixed, and associations that appear in crude comparisons have sometimes disappeared once maternal age, education and smoking were accounted for.
Indoor factors with evidence
| Factor | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Particulate matter (PM₂.₅ and PM₁₀) | difference 24 per 10 % | 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-0171 Association Between Individual Air Pollution (PM10, PM2.5) E… (2024) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | difference 27 per 10 % | 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-0172 Association Between Individual Air Pollution (PM10, PM2.5) E… (2024) | machine |
| Air purifiers | OR 0.92 (0.87–0.98) | — · 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-1670 Inadera Association of air purifier usage during pregnancy with adve… (2024) | machine |
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Cite this page
Coridum Research. Preterm birth. Coridum Knowledge G-0162, 16 September 2026. https://coridum.com/k/G-0162/