Individual and joint effects of prenatal green spaces and PM2.5 exposure on BMI Z-score of children: a birth cohort study

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BACKGROUND AND AIM: Few studies examined the association of prenatal exposure to green spaces with children’s body mass index (BMI) Z-score, and no study evaluated the joint effect of prenatal green spaces and PM2.5 exposure on children’s BMI Z-score. We aimed to assess the individual and joint effect of prenatal green spaces and PM2.5 exposure on BMI Z-score of children. METHODS: The study was based on a birth cohort (2014-2017) in Beijing, China, in which 13,688 mother and their children were included. We estimated prenatal exposure to green spaces by calculating averaged normalized difference vegetation index with 500m buffers (NDVI-500), and prenatal PM2.5 exposure based on maternal residential addresses. Weight and height were measured at approximately 2 years old. We calculated BMI Z-score and defined overweight and obesity based on the WHO Standards. Generalized linear regression was used to examine the individual and joint effects of prenatal NDVI-500 and PM2.5 exposure on children’s BMI Z-score and overweight or obesity. RESULTS:A 0.1 increase in prenatal NDVI-500 exposure and a 10 µg/m3 decrease in PM2.5 were associated with 0.192 [95% confidence interval (95%CI): 0.158, 0.225] and 0.020 (95%CI: 0.001,0.040) increase of children’s BMI Z-score, respectively. Compared with exposed to low-level NDVI-500 and high-level PM2.5, the BMI Z-score was higher in children whose mother exposed to high-level of NDVI-500 (greater than median) and low-level PM2.5 (not greater than median) [β:0.163 (95%CI: 0.117, 0.209), Pinteraction=0.025]. We did not observe significant associations of NDVI-500 and PM2.5 with the risk of overweight or obesity. CONCLUSIONS:The study suggested the beneficial effect of prenatal exposure to green spaces on children’s growth and its interaction with PM2.5. The findings call for developing public health policy to improve green infrastructure and control PM2.5 concentrations, in order to promote children’s growth. KEYWORDS: Prenatal exposure, green spaces, PM2.5, body mass index, children, growth