<p>Previous research exploring the green spaces – birth outcomes relationships is inconclusive, predominantly focusing on affluent countries and often neglecting the effect of healthcare accessibility. This study evaluates the link between green space and small for gestational age (SGA), a critical type of adverse birth outcome, while accounting for the effect of healthcare accessibility. We compiled a dataset of 1,436,480 singleton term newborns delivered between 2014 and 2016 in Hubei Province, China. Exposure to green space is quantified by the Normalized Difference Vegetation Index (NDVI), and healthcare accessibility is assessed through the generalized two-step floating catchment area method. Several mixed-effects logistics regression models are implemented to evaluate the associations among green space, healthcare accessibility and SGA. Our results show that, after adjusting for sociodemographic factors and pollution exposure, green space exposure fails to provide consistent and significant benefits for SGA. These results hold across various stratified analyses, including samples stratified by income, urban-rurality, and levels of air pollution. Regarding healthcare accessibility, we find that higher healthcare accessibility significantly reduces the risks of SGA in the middle region, with no such effects identified for the eastern and western regions.</p>