A recent study has found that living in a green neighbourhood may have a positive impact on birth outcomes. Pregnant women who live in neighbourhoods with plenty of grass, trees and other greenery are more likely to give birth at term, and have babies who are born at higher birth weights, than women who live in less green, urban areas.
The study, from Oregon State University and the University of British Columbia, compared 64,000 births in the Vancouver, British Columbia area between 1999 and 2002. Researchers used satellite imaging to compare the greenery in each woman's neighbourhood, by focusing on the amount of vegetation within 100 metres of her home. The results were adjusted to make sure factors such as neighbourhood income, noise, exposure to air pollution, distance to the nearest park and neighbourhood walkability did not create a bias in the results. Even factoring in each of these considerations, the results stood firm that living in a greener neighbourhood increased the likelihood of a woman birthing at full term and having a heavier baby.
“This was a surprise,” said Perry Hystad, an environmental epidemiologist and lead author of the study. “We expected the association between greenness and birth outcomes to disappear once we accounted for other environmental exposures such as air pollution and noise. The research really suggests that greenness affects birth outcomes in other ways, such as psychologically or socially.”
The research, published in a recent edition of the journal Environmental Health Perspectives, identified that the risk of very pre-term births decreased by 20%, and the risk of moderate pre-term births decreased by 13% for women living in greener neighbourhoods. The study also found that babies born to women living in greener neighbourhoods were less likely to be considered small for their gestational age. In fact, women from the greener neighbourhoods had babies who weighed around 45g more at the birth than the infants from less green, urban neighbourhoods.
“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.
The exact reasons for these findings is not yet known, and more study is needed to determine the cause of the improved birth outcomes. The researchers were unsure whether the green space provided more social opportunities, enabling people to feel more secure within their community, or whether it had a psychological effect by reducing stress and depression.
Half of the world's population live in urban areas, and it is important to assess the impact of this upon human health. Green spaces are already known to reduce mental health problems, reduce blood pressure and increase life expectancy. The World Health Organisation has estimated that as many as 60% of the world's population will live in urban areas by 2050, this works out as approximately 6.4 billion people.
There is an increased cost associated for healthcare companies with caring for pre-term and underweight babies. Babies born before term or underweight have an increased risk of health and developmental problems not just at birth, but as they continue to grow.
“Planting one tree likely won't help, you don't really see the beneficial effects of green space until you reach a certain threshold of greenness in a neighbourhood.” Hystad said, “We know green space is good. How do we maximise that benefit to improve health outcomes? The answer could have significant implications for land use planning and development.”
Understanding more about how green neighbourhoods can affect health can influence policy, improve education, encourage positive lifestyle choices and, even, perhaps in this case, influence town planning and design. This study is important because it may shed light on a potentially simple and effective way to impact upon the population's health, simply by creating greener neighbourhoods.
The study did not identify how much or what type of green space was most effective for improved birth outcomes. More research is needed to learn more about the importance of green spaces for birth outcomes, and the types of green spaces that lead to the best outcomes. More research is also needed to understand why women in greener neighbourhoods see better birth outcomes.