Plant species richness, green spaces, and preterm birth risk in urban areas

Mengyi Li; Qiping Fan; Yi Sun; Tarik Benmarhnia; Jiu-Chiuan Chen; Anqi Jiao; John Molitor; David A Sacks; Jeff M Slezak; Vicki Y Chiu; Chantal C Avila; Darios Getahun; Jun Wu

doi:10.1016/j.envint.2025.109644

Plant species richness, green spaces, and preterm birth risk in urban areas

Environ Int. 2025 Jun 25:202:109644. doi: 10.1016/j.envint.2025.109644. Online ahead of print.

Authors

Mengyi Li¹, Qiping Fan², Yi Sun³, Tarik Benmarhnia⁴, Jiu-Chiuan Chen⁵, Anqi Jiao¹, John Molitor⁶, David A Sacks⁷, Jeff M Slezak⁸, Vicki Y Chiu⁸, Chantal C Avila⁸, Darios Getahun⁹, Jun Wu¹⁰

Affiliations

¹ Department of Environmental and Occupational Health, Joe C. Wen School of Population & Public Health, University of California, Irvine, CA, USA.
² Department of Public Health Sciences, Clemson University, Clemson, SC, USA.
³ Department of Environmental and Occupational Health, Joe C. Wen School of Population & Public Health, University of California, Irvine, CA, USA; Institute of Medical Information, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
⁴ Scripps Institution of Oceanography, University of California, San Diego, CA, USA; Irset Institut de Recherche en Santé, Environnement et Travail, UMR-S 1085, Inserm, University of Rennes, EHESP, Rennes, France.
⁵ Departments of Population & Public Health Sciences and Neurology, University of Southern, California, Keck School of Medicine, Los Angeles, CA, USA.
⁶ College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
⁷ Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA; Department of Obstetrics and Gynecology, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA.
⁸ Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA.
⁹ Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA; Department of Health Systems Science, Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, CA, USA.
¹⁰ Department of Environmental and Occupational Health, Joe C. Wen School of Population & Public Health, University of California, Irvine, CA, USA. Electronic address: junwu@hs.uci.edu.

PMID: 40578112
DOI: 10.1016/j.envint.2025.109644

Abstract

Background: Growing evidence suggests that urban biodiversity may influence human health, though this relationship remains incompletely understood. While green spaces have shown beneficial effects on birth outcomes, the specific role of plant species richness has not been investigated in relation to preterm birth (PTB, <37 weeks' gestation).

Methods: Using Kaiser Permanente Southern California electronic health records (2015-2021), we analyzed 232,452 births to examine associations between plant species richness and PTB. Plant species richness was assessed at the maternal neighborhood level, defined using circular buffers of 1.5 km around maternal residences.

Results: We found that increased plant species richness was associated with decreased PTB risk (adjusted odds ratio per interquartile range: 0.959, 95 % CI: 0.941, 0.977). The observed association persisted after further adjustment for multiple green space indicators. The proportions of mediation effects attributable to mean temperature during pregnancy ranged from 7.0 % to 7.8 % across plant species diversity indicators. In the subgroup analysis, plant species diversity demonstrated significantly stronger protective associations against PTB among mothers exposed to higher levels of Ozone, high ambient temperatures, and those gave birth during the pandemic period. Conversely, protective associations were more pronounced among mothers with lower NO₂ exposure during pregnancy. Notably, the significant relationship between plant species richness and reduced PTB persisted in pandemic-period analyses after adjusting for COVID-19 infection during pregnancy.

Conclusions: Our findings highlight a complex interplay of sociodemographic and environmental factors influencing PTB risks and underscore the critical need for public health interventions that consider the unique attributes of urban green space.

Keywords: Biodiversity; Green space; Maternal exposure; Plant species richness; Pregnancy outcome; Preterm birth.