Residential green space is associated with higher birth weight

There is scientific evidence that maternal exposure to natural environments supports healthy foetal growth. However, the results of studies published so far have been heterogeneous across regions and there is very little research on the effects of blue spaces such as rivers, the sea or lakes. A new study involving a team from the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, assessed the associations between maternal exposure to green and blue spaces during pregnancy and birth outcomes in 11 birth cohorts from nine European countries, including Spain.

The results of the study, published in the journal Environment International, indicate that proximity to green space around the home is associated with higher birth weight and lower odds of having a small-for-gestational-age baby, or SGA, as newborns whose birth weight is less than or equal to the 10th percentile are called. In contrast, greater distance to residential green space was associated with lower birth weight and higher odds of SGA. Associations for accessibility to green space and exposure and accessibility to blue space were close to zero.

"Ensuring healthy foetal growth is essential to prevent many adverse health consequences, both early and later in life," says Maria Torres, first author of the study. "For example, babies with low birth weight or small for gestational age may have an increased risk of growth problems, lower IQ and premature death in childhood, as well as obesity, cardiovascular disease and diabetes in adulthood.

This study, part of the LifeCycle project, was based on a sample of 69,683 newborns, with an average birth weight of 3.42 kg, of whom 6.6% were classified as SGA. For each participant, seven indicators of residential exposure to natural environments were calculated: green space within 100, 300 and 500 metres of the household - calculated using the Normalised Difference Vegetation Index (NDVI) -, distance to the nearest green space, accessibility to green space, distance to the nearest blue space and accessibility to blue space.

The research team also assessed the possible effect modification by socio-economic status (SES) and region of Europe. The results indicate stronger associations between residential green space and higher birth weight for participants with lower educational levels, from more deprived areas and living in Northern Europe.

The findings of this study are in line with previous research from various regions around the world. A growing number of studies have reported associations between maternal exposure to green spaces and higher birth weight. However, most of these studies were conducted in a single country with a particular climate and vegetation type, and estimates of the effect differed from region to region. "Capitalising on data from 11 birth cohorts across Europe allowed us to assess, for the first time, this association in different countries and shed light on the role of region in this issue", explains Payam Dadvand, ISGlobal researcher and senior author of the study.

The research involved participants from the Netherlands, the United Kingdom, Denmark, France, Spain, Lithuania, Norway, Italy and Greece. According to the authors, the results support the implementation of policies to promote natural environments in our cities, starting with the most disadvantaged areas. "Having accessible natural environments in our cities could benefit the health of our children from before birth and beyond, and this should be taken into account by urban designers," concludes Maria Torres.

Reference

Torres M, Avraam D, Cadman TJ, Fossati S, de Castro M, et al. Exposure to natural environments during pregnancy and birth outcomes in 11 European birth cohorts. Environment International. Volume 170, December 2022, 107648. https://doi.org/10.1016/j.envint.2022.107648