Association of exposure to residential greenness with semen quality: A retrospective longitudinal study of sperm donation volunteers in Guangdong province, China

https://doi.org/10.1016/j.ecoenv.2021.112396Get rights and content
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Highlights

  • First study investigating the association between residential greenness and semen quality.

  • Our findings suggest that residential greenness exposure may improve semen quality.

  • The association of residential greenness with semen quality varies across age and season.

Abstract

Background

Exposure to residential greenness has been associated with benefits on certain reproductive health outcomes. However, its potential benefits on semen quality remain unknown.

Objectives

To quantitatively explore the association between exposure to residential greenness and semen quality.

Methods

We investigated 9142 sperm donation volunteers who underwent 38,682 semen examinations at Guangdong provincial human sperm bank in China during 2016–2019. Exposure to residential greenness was assessed using mean daily Normalized Difference Vegetation Index (NDVI) at each subject’s residential address with a 400 m buffer during 0–90 days before each semen collection. Multivariate linear mixed models and linear regression models were used to assess the association between exposure to residential greenness and semen quality.

Results

An interquartile range increase in exposure to residential greenness was significantly associated with a 0.034 (95% confidence interval [CI]: 0.005, 0.063) ml, 4.06 (95% CI: 0.76, 7.37) × 106, and 0.32% (95% CI: 0.22%, 0.41%) increase in semen volume, total sperm number, and normal forms, respectively; similar trends were observed across quartiles of exposure to residential greenness (all p-values for liner trend <0.05 except for semen volume). The association of greenness exposure with semen volume and total sperm number was stronger in subjects 18–25 years, while the association with normal forms was stronger in subjects 26 years or older. The association for sperm concentration, total sperm number, and normal forms were stronger in cool season, while the association for semen volume was stronger in warm season.

Conclusion

We found that exposure to residential greenness was significantly associated with higher semen quality. Further studies are warranted to determine the causality of the association and its underlying mechanisms.

Keywords

Residential greenness
Semen quality
Sperm donation volunteer
Male reproduction
Exposure-response association

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These authors contributed equally to this work.