New research from Drexel University’s Dornsife School of Public Health adds to the growing body of evidence linking proximity to greenspaces, such as parks and trees, with healthier birth outcomes. This study, published in Science of The Total Environment, delves deeper by accounting for variables like education, income, and body mass index, and explores the specific impact of newly planted trees on maternal and newborn health.
Study Overview and Methodology
The research is based on an innovative dataset from Portland, Oregon, where more than 36,000 trees were planted between 1990 and 2020 by the nonprofit group Friends of Trees. The study examined how the number of newly planted trees within 100 meters of a mother’s home influenced birth outcomes for babies born between January 1, 2015, and December 31, 2020. The researchers controlled for various factors known to influence birth weight, such as race, whether the pregnancy was the mother’s first, body mass index (BMI), and education level.
Key Findings
The study found a significant link between the number of newly planted trees and positive birth outcomes. Specifically, the researchers observed:
Higher birth weights: Each tree planted within 100 meters of a mother’s home over the 10 years before her child’s birth was associated with a 2.3-gram increase in birthweight.
Lower risk of small-for-gestational-age births: A higher number of trees was linked to a decreased risk of babies being born small for their gestational age.
Decreased risk of pre-term birth: The proximity to trees was also associated with a reduction in preterm birth rates.
For example, the presence of at least 10 trees within 100 meters of a mother’s home was associated with a 50-gram increase in birth weight, which may seem modest but can have significant implications for public health. A 50-gram increase in birth weight across all babies in the study could lead to 642 fewer babies considered small for gestational age — a group at higher risk for developmental delays and long-term health issues.
Unlike previous studies that only focused on existing greenspaces, this research emphasizes the role of newly planted trees in promoting maternal and infant health. Yvonne Michael, ScD, senior author of the study, noted that even newly planted trees contribute to healthy birth outcomes. “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 said.
The research also suggests that older, established trees may provide additional benefits by reducing road noise and air pollution, which can negatively impact pregnancy. Additionally, older trees may offer psychological restoration, promoting relaxation and reducing stress for residents. Stress is a well-documented factor in preterm birth and poor health outcomes, so the potential psychological benefits of trees cannot be understated.
One of the challenges in studying the effects of tree cover is that existing trees are often closely tied to socioeconomic factors, such as income and education. This can create bias in studies examining birth outcomes. However, the current research circumvented this issue by focusing on newly planted trees, thus providing a more accurate picture of their potential impact.
Additionally, the researchers found that established trees, not newly planted ones, were more effective at mitigating the negative effects of road density on birth weight. This is likely due to the more developed leaves of older trees, which are better equipped to combat air pollution and noise pollution.
While the study showed a positive correlation between trees and healthier newborns, the authors acknowledged that rising air temperatures and wildfire smoke in 2020 may have contributed to some of the observed declines in birthweight. However, the overall trend remained significant, indicating the positive impact of trees on public health.
While the study provides strong evidence of the link between newly planted trees and healthier birth outcomes, the researchers call for further studies, including randomized controlled trials, to definitively establish causality.
This research follows a growing body of work on the benefits of greenspaces for public health. A previous study by Michael and colleagues in 2013 found that the loss of 100 million trees due to an invasive pest, the emerald ash borer, led to increased rates of heart disease deaths and lower respiratory illnesses in affected areas.
You Might Be Interested In:
- Tanning While Pregnant: Is It Dangerous?
- Birth Control Fails: 8 Ways You Can Still Get Pregnant
- Can You Get Pregnant from the Pull-Out Method? What to Know
