An American study published in April 2025 by Geoffrey H. Donovan and his team in Science of the Total Environment reveals that the presence of newly planted trees around the maternal home is significantly associated with better birth results: higher weight, reduction of premature births and intrauterine growth delays. This link sheds light on the unknown role of urban nature in perinatal health, at the crossroads of environmental epidemiology, town planning and public health.
A question of foliage, not just fortune
The inequalities of health at birth are well documented: ethnic origin, level of education, air pollution or noise play an important role. But these factors are not the only ones in question. Many recent studies have shown that a more “green” environment – parks, trees, lawns – is associated with healthier pregnancies. Donovan’s novelty of the work is to isolate the impact of the recent plantation trees, regardless of the vegetation already present.
The study focused on more than 4 million living births in the United States. The researchers crossed public health data with the municipal trees for the planting of trees. By measuring the number of trees planted within a radius of 100 meters around maternal homes in the last 10 years, they have observed measurable and constant effects on perinatal outcome.
Measurable effects on births
Among the notable results:
- +2,3 grammes On average birth weight for each tree planted nearby.
- -4,3 % risk of birth of a baby “little for gestational age” (SGA, Small for Gestational Age).
- -4,9 % of premature birth risk (before 37 weeks of gestation).
These results are robust: they hold after statistical adjustment on dozens of socio -demographic variables (mother’s age, income, origin, education) and environmental (level of pollution, urban density, pre -existing tree cover). The fact that the effects are associated with Recently planted treesand not to an ancient and potentially greenery linked to easier districts, strongly limits the risk of biases.
What biological mechanisms?
How can the planting of trees improve pregnancy conditions? Several convergent hypotheses emerge:
-- Reduction of maternal stress : The view of greenery and contact with nature are known to reduce cortisol, stress hormone, whose excess during pregnancy are linked to complications (hypertension, fetal growth retardation).
- Air quality improvement : The trees capture fine particles (PM2.5), nitrogen oxides and ozone, which negatively affect fetal development.
- Attenuation of heat islands : Wooded canopies reduce local temperatures, which is particularly beneficial during heat waves, known to increase the risk of premature delivery.
- Promotion of physical activity : Pregnant women living near green spaces are more likely to walk regularly, which promotes better metabolic health.
Implications for public health and town planning
This study brings a weight argument to integrate urban greening policies into public health strategies, especially in disadvantaged neighborhoods. The planting of trees is not simply a landscaping embellishment: it is a low -cost intervention, durable, and with multiple effects.
Certain municipalities such as Portland (Oregon) or Louisville (Kentucky) have already integrated these results into their urban planning plans. Target green programs in low health areas could reduce inequalities from birth.
A paradigm change?
Donovan’s study joins a broader current of research in environmental health, which no longer considers nature as a simple decor but as An active determinant of human health. The trees become silent actors in prenatal development, offering babies a departure in a little more robust life, simply by their presence.
| Region | Birth weight | Prematurity | Advanced mechanisms |
|---|---|---|---|
| North America | +2 to +25 g/tree | -4 to -7 % | Pollution, stress, temperature |
| Europe | +20 to +44 g | -4 to -6 % | Social inequalities, accessibility, perceived quality |
| Asia | +20 to +40 g | -5 % env. | Pollution attenuation, thermal regulation, stress |
| Oceania | +30 to +50 g | -15 to -20 % | Physical activity, social ties, almost omnipresent nature |
A global public health lever
The benefits of urban greening on perinatal health are now largely confirmed internationally. If they vary in intensity according to urban, cultural and environmental contexts, all works converge on the same conclusion: The presence of greenery around the maternal home acts as a powerful protective factoraccessible et modifiable.
The challenge is now to transform this knowledge into active policyespecially in the most vulnerable districts, by integrating nature into public health and urban planning plans.
References:
- Donovan, G.H. et al. (2025). Tree planting and perinatal health outcomes: A nationwide cohort study in the United States. Science of the Total Environment. DOI: lien PubMed
- Hu, C. Y., et al. (2021). Greenspace exposure during pregnancy and birth outcomes: A systematic review. Environmental Health Perspectives.
- Dzhambov, A. M., et al. (2020). Urban green spaces’ effects on birth outcomes: A systematic review and meta-analysis. Environmental Research.
