Noise pollution affects fetal growth, embryonic size, and birth outcome during pregnancy, reveals ultrasound study

The study further showed that reducing total noise exposure during pregnancy partially mediated the association between greenness exposure and small embryonic size exposure.

Previous studies have indicated that exposure to noise during pregnancy was not linked with adverse birth outcomes. However, no studies have assessed the association between noise exposure and fetal and embryonic growth or mutually evaluated other urban environmental exposures, such as traffic-related air pollution or natural spaces.

Against the above background, Naomi Graafland, University Medical Centre, Rotterdam, The Netherlands, and colleagues examined the association between exposure to total residential noise (i.e. railway, road traffic, industry, and aircraft), railway noise, road traffic exposure during pregnancy and birth outcomes and fetal growth parameters in a large population-based prospective cohort study. They also investigated whether an association between noise exposure and a specific outcome identified in the first aim was confounded by exposure to traffic-related air pollution or whether traffic-related air pollution exposure modified the observed association. Lastly, they determined whether noise exposure mediated a possible association between exposure to greenness or distance to blue spaces and any outcomes described.

A total of 7947 pregnant women were included in the Generation R Study in the Netherlands. The researchers retrieved information on adverse birth outcomes (small for gestational age, low birth weight, and preterm birth) and neonatal anthropometrics at birth (weight, length, and head circumference) from medical records. Fetal growth parameters (femur length, head circumference, and estimated fetal weight) and embryonic size (crown-rump length) were measured at several gestational ages using ultrasound. Environmental noise maps estimated the total, railway, and road traffic noise at the participants' home addresses during pregnancy.

The authors reported the following findings:

• During pregnancy, higher total noise exposure was associated with a more significant crown-rump length (0.07 SDS).
• No associations were observed with neonatal anthropometrics, adverse birth outcomes, and fetal growth parameters. Similar results were seen for road traffic noise exposure, while railway noise exposure was not linked with any outcomes.
• Traffic-related air pollution was not linked with crown-rump length.
• 15% of the association between greenness exposure and smaller crown-rump length was mediated by total noise exposure.

"During pregnancy, exposure to outdoor residential noise was associated with larger embryonic size," the authors stated. "Moreover, total noise exposure reduction during pregnancy partially mediated the association between greenness exposure and smaller size of the embryo."

"Additional studies are warranted to confirm and further understand these novel findings," they concluded.

Reference:

Graafland, N., Essers, E., Posthumus, A., Gootjes, D., Ambrós, A., Steegers, E., & Guxens, M. (2023). Exposure to outdoor residential noise during pregnancy, embryonic size, fetal growth, and birth outcomes. Environment International, 107730. https://doi.org/10.1016/j.envint.2023.107730