Mid-to-late pregnancy: A critical window for the protective effect of green space against autism spectrum disorder (ASD).

Green space exposure during mid-to-late pregnancy (6 to 1 month before birth) is linked to significantly lower odds of ASD in children, independent of PM2.5 levels.

• Why it matters: Understanding specific sensitive periods for green space's protective effects can improve prenatal care and urban planning strategies to reduce ASD risk.
• What they did: A matched case-control study of 207 children with ASD and 621 controls used satellite-derived NDVI data and statistical models to identify critical exposure windows and assess PM2.5's mediating role.
• The result: Children with ASD had lower NDVI values than controls across all 14 months studied, with no evidence that PM2.5 mediated this relationship, highlighting the importance of green space during mid-to-late pregnancy.