The modifying role of residential greenness on the association between heat waves and adverse birth outcomes: Results from the ELEFANT project

Yuxuan Ma; Yuanyuan Yu; Lei Zhao; Qisijing Liu; Jiayan Ni; Zi Lin; Bin Chen; Weixia Li; Huishu Lin; Yuhong He; Shuhao Shi; Jianqiong Zheng; Hongping Zhang; Chen Li; Furong Deng; Shike Hou; Tailang Yin; Yan Zhou; Liqiong Guo

doi:10.1016/j.envres.2025.121118

The modifying role of residential greenness on the association between heat waves and adverse birth outcomes: Results from the ELEFANT project

Environ Res. 2025 Apr 15:271:121118. doi: 10.1016/j.envres.2025.121118. Epub 2025 Feb 12.

Authors

Yuxuan Ma¹, Yuanyuan Yu¹, Lei Zhao¹, Qisijing Liu², Jiayan Ni³, Zi Lin¹, Bin Chen⁴, Weixia Li¹, Huishu Lin¹, Yuhong He¹, Shuhao Shi¹, Jianqiong Zheng⁵, Hongping Zhang⁵, Chen Li⁶, Furong Deng⁷, Shike Hou¹, Tailang Yin⁸, Yan Zhou⁹, Liqiong Guo¹⁰

Affiliations

¹ School of Disaster and Emergency Medicine, Tianjin University, Tianjin, 300072, China; Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, 325000, China; Tianjin Key Laboratory of Disaster Medicine Technology, Tianjin University, Tianjin, 300072, China.
² Research Institute of Public Health, School of Medicine, Nankai University, Tianjin, 300071, China.
³ The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China.
⁴ Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, 325000, China; Tianjin Key Laboratory of Disaster Medicine Technology, Tianjin University, Tianjin, 300072, China.
⁵ Wenzhou People's Hospital, Wenzhou, Zhejiang 325000, China.
⁶ Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin, 300070, China.
⁷ Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China.
⁸ Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, China. Electronic address: reproductive@whu.edu.cn.
⁹ School of Disaster and Emergency Medicine, Tianjin University, Tianjin, 300072, China; Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, 325000, China; Tianjin Key Laboratory of Disaster Medicine Technology, Tianjin University, Tianjin, 300072, China. Electronic address: zhouyantj@tju.edu.cn.
¹⁰ School of Disaster and Emergency Medicine, Tianjin University, Tianjin, 300072, China; Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, 325000, China; Tianjin Key Laboratory of Disaster Medicine Technology, Tianjin University, Tianjin, 300072, China. Electronic address: yingqidao@163.com.

PMID: 39952460
DOI: 10.1016/j.envres.2025.121118

Abstract

Background: The impact of heat waves on perinatal outcomes has become a focus of attention. However, the association between heat waves and preterm birth (PTB), low birth weight (LBW), small for gestational age (SGA) and large for gestational age (LGA) remains controversial. Furthermore, whether residential greenness can mitigate the adverse effects of heat waves on birth outcomes still unclear.

Methods: This study employed a retrospective cohort design based on data from the ELEFANT project, conducted in Tianjin, China, spanning from 2011 to 2019. We assessed heat waves exposure by creating 12 definitions of extreme heat with varying relative temperatures (90th, 95th, 97.5th and 99th percentiles) and durations (at least 2, 3, or 4 consecutive days). Residential greenness levels were evaluated using the MODIS Normalized Difference Vegetation Index (NDVI). Cox proportional hazards regression models were fitted to estimate the risks of PTB, LBW, SGA and LGA in relation to heatwaves exposure and the multiplicative and additive interactions of heat waves and greenness on adverse birth outcomes across different pregnancy periods, including pre-pregnancy.

Results: Our findings indicate that heatwaves significantly increase the risks of PTB by 2.4%-15.6%, LBW by 7.6%-18 %, SGA by 3.6%-88.4%, and LGA by 2%-3.4%. The lack of residential greenness exhibited a synergistic interaction with heatwaves on PTB, SGA and LGA (RERI >0), especially during milder heat events during entire pregnancy. For LBW, interactions between greenness and heatwaves were limited. Furthermore, we identified that heatwave was significantly associated with high risk of adverse birth outcomes among mothers living in rural areas.

Conclusions: Prioritizing greenspace can help mitigate the effects of heatwaves, offering a viable and cost-effective approach to protecting maternal and fetal health.

Keywords: Heat waves; Large for gestational age; Low birth weight; Preterm birth; Residential greenness; Small for gestational age.

MeSH terms

Adult
China / epidemiology
Extreme Heat* / adverse effects
Female
Hot Temperature* / adverse effects
Humans
Infant, Low Birth Weight
Infant, Newborn
Infant, Small for Gestational Age
Pregnancy
Pregnancy Outcome* / epidemiology
Premature Birth* / epidemiology
Retrospective Studies