Pregnant women who live in neighbourhoods with plenty of grass, trees or other green vegetation are more likely to deliver at full term and their babies are born at higher weights, compared to moms who live in urban areas that are not as green, a new study has found.
The findings held up even when results were adjusted for factors such as neighbourhood income, exposure to air pollution, noise, and neighbourhood walkability, according to researchers at Oregon State University and the University of British Columbia.
"We expected the association between greenness and birth outcomes to disappear once we accounted for other environmental exposures such as air pollution and noise," said Perry Hystad, an environmental epidemiologist in the College of Public Health and Human Sciences at Oregon State and lead author of the study.
"The research really suggests that greenness affects birth outcomes in other ways, such as psychologically or socially," Hystad said.
More study is needed to determine if additional green space provides more social opportunities and enhances a person's sense of belonging in the community, or if it has a psychological effect, reducing stress and depression, Hystad said.
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Researchers studied more than 64,000 births in the Vancouver, British Columbia, area between 1999 and 2002. They found that very pre-term births were 20 % lower and moderate pre-term births were 13 % lower for infants whose mothers lived in greener neighbourhoods.
They also found that fewer infants from greener neighbourhoods were considered small for their gestational age. Babies from the greener neighbourhoods weighed 45 grams more at birth than infants from less green neighbourhoods, Hystad said.
"From a medical standpoint, those are small changes in birth weight, but across a large population, those are substantial differences that would have a significant impact on the health of infants in a community," Hystad said.
Babies born early or underweight often have more health and developmental problems, not just at birth but also as they continue to grow up, and the cost to care for pre-term and underweight infants also can be much higher, Hystad said.
The study is published in the journal Environmental Health Perspectives.