Greener neighborhoods support healthier birth weights, UIC study suggests

Time and time again, studies have shown that proximity to nature benefits your health. Now, research from the University of Illinois Chicago finds that nature can positively affect you even before you're born.

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A study from the Children's Environmental Health Initiative, a research, education and outreach program led by UIC Chancellor Marie Lynn Miranda, found that women living in greener neighborhoods gave birth to babies with higher birth weights, a positive indicator of a baby's health. The study was published in the journal Environment International.

"This is a rare good-news story," said Melissa Fiffer, senior research scientist and first author of the study. "Pregnancy and early childhood are critical times in our lives, so we think about maternal and child health as more sensitive to exposures. In this study, we have evidence for a potentially beneficial exposure in the neighborhood environment: how green the area around your home is."

The positive effect was evident even when Fiffer and her colleagues factored in negative environmental factors, such as air pollutants and temperature. Despite these variables that are known to be negatively associated with birth weight, greenness still was beneficial.

"Greenness near your home and in your neighborhood had a protective effect or a positive association with the birth weight of the baby, regardless of all those things that might contribute negatively," Fiffer said.

Boosting well-being

Proximity to nature boosts health in several ways. For one thing, living near green spaces like parks, trails or forest preserves may make it likelier you'll visit those places for exercise, Fiffer said. "That could have direct effects related to your risk for cardiometabolic diseases or other health outcomes that are associated with your physical activity."

Melissa Fiffer, senior research scientist with UIC's Children's Environmental Health Initiative. (Photo: Ariana Raghian) UIC Chancellor Marie Lynn Miranda leads the Children's Environmental Health Initiative. (Photo: Mike Fan)

Living in a greener neighborhood may also reduce adverse environmental exposures, as green spaces replace pollution sources.

Access to green space also opens opportunities for social connections, Fiffer said. "There's been a lot of work showing the importance of social connections on your overall health," she said.

And being in nature can be relaxing and rejuvenating. "Being in a greener area, you might actually have better stress recovery or stress response," Fiffer said. Healthy moms, and healthy pregnancies, lead to healthier babies.

Satellites and birth records

In their new study, the researchers looked at the connection between greenness around the mother's home and birth weight, which is an indicator of a baby's future health. "Low birth weight can be predictive of longer-term development, including neurological development and pulmonary development," Fiffer said. "It's become a predictor of other health concerns, particularly cardiometabolic disease, later in life."

These data came from detailed birth records in Michigan from 2007-16. To measure greenness, the researchers used Landsat data gathered from NASA and U.S. Geological Survey satellites. These satellites detect how much green vegetation is in an area, which collaborators used to calculate a quantity called the Normalized Difference Vegetation Index. "It's a measure of what is photosynthetically active vegetation in that spot, or how green is that spot," Fiffer said.

For each area around a pregnant woman's residence, representing the greenness surrounding home and on a short walk or drive, the researchers mapped the corresponding greenness values. From there, they analyzed the associations between greenness and birth weight, and how other environmental factors played a role.

A three-trimester effect

In a previous study, the team used the Michigan birth data to investigate the impact on birth weight of two air pollutants: fine particulate matter and nitrogen dioxide. The study, led by Children's Environmental Health Initiative research affiliate Mercedes Bravo, found weekly windows in the three trimesters of pregnancy when women were more sensitive to the contaminants. "It really may matter when during the pregnancy you have these exposures," Fiffer said.

But in the new study, the team didn't find that certain windows in the pregnancy were more or less affected by exposure to green space, Fiffer said. In their modelling, they also accounted for other measures of temporality, including season and year of birth. "Across all trimesters of pregnancy, no matter the timing, greenness had a positive effect on birth weight," Fiffer said.

"I hope this idea contributes to the growing body of evidence that having contact with nature during pregnancy can be a positive thing," she said. "There could be some considerations in the design of preventive interventions for pregnant women such as urban greening, mindfulness and meditation practices in nature and nature walking groups, with input from urban planners and clinicians."

Bringing the research to Illinois

Fiffer and her colleagues want to expand their investigations of health impacts of greenness. The Children's Environmental Health Initiative is collaborating with fellow researchers in UIC's Center for Extreme Conditions and Health Excellence, led by School of Public Health professor Kristen Malecki and College of Liberal Arts and Sciences professor Miquel Gonzalez-Meler. Together, these teams are studying novel measures of green space in and around Chicago, like tree surveys done through the Morton Arboretum and models assessing how vegetation affects Chicago microclimates developed by the Community Research on Climate and Urban Science project, or CROCUS.

Fiffer co-leads the Center for Extreme Conditions and Health Excellence's geospatial data and analysis core, which is cataloging these data resources. "We're thinking about how we can best capture green space and how we measure it to advance weather and health research and inform potential nature-based solutions," she said.

In addition to Fiffer and Miranda, Dominique Zephyr, Joshua Tootoo and Rafiga Gasymova from the Children's Environmental Health Initiative at UIC are co-authors on the paper.