But proximity to nature also has an impact on the number of premature births, according to a recent US study published in the journal Science of the Total Environment.
Conducted by professors at Drexel University in Philadelphia, this research followed over 36,000 pregnant women who gave birth between Jan 1, 2015, and Dec 31, 2020, residing in Portland, Oregon, where over 36,000 trees were planted between 1990 and 2020. The number of trees planted within a 100m radius of the participants’ addresses was evaluated.
“We found that tree planting around maternal address was associated with increased birthweight as well as a reduced probability of a small-for-gestational-age or preterm birth,” the researchers wrote.
In other words, mothers living in areas where trees were planted within the past 30 years were more likely to give birth at term, with babies of higher birth weights, than those living farther away from tree-planted areas.
Specifically, living within 100m of at least 10 trees is associated with an increase of about 50g in birth weight, which was the case for 2,879 babies in the sample studied.
“This might not seem like a lot, but if every baby in our sample gained 50g at birth, that means 642 fewer babies considered small for gestational age and at higher risk for worse development later in life,” said senior author Yvonne Michael.
The study also notes that older trees may provide some additional benefits compared to those recently planted, such as improved air quality and reduced noise pollution from road traffic.
This study isn’t the first to highlight a link between a reduction in premature births and proximity to green space. But the novelty lies in its methodology, which focuses on recently planted trees and over a precise period.
“Existing tree cover is often closely tied to factors like income, education and race, making it difficult to fully account for other possible explanations when studying birth outcomes. By focusing on newly planted trees, we were able to reduce the bias – essentially treating it as a natural experiment,” Michael explained.
“This is another data point showing that planting trees is a relatively easy and low-cost way to improve public health from the earliest stages of life,” she concluded.