Table 1.

Search terms used for the systematic search. Use of “AND” or “OR” in the search engines has been indicated.

	Horizontal lines divided by “AND”
	Cases	Outcome
Search terms (Vertical lines divided by “OR”)	Neurodevelopmental disorders[MESH] Attention Deficit Disorder*[Text Word] Attention Deficit Hyperactivity Disorder[Text Word] ADHD[Text Word] ADD[Text Word] Autism[text word] “Autism Spectrum Disorder”[MESH] Neurodevelopmental*[text word] Neurodevelopmental disorder[MESH]	(Microbiology[MESH] OR Microbiology[Subheading] OR Microbiology[Text Word])AND(Feces”[MESH] OR Gastrointestinal Tract[MESH]) Gastrointestinal Microbiome[MESH] Gastrointestinal Microbiome*[text word] Gastrointestinal Microbiot*[text word] Gut microbiot*[text word] Gut microbiome*[text word] Intestinal Microbiot*[text word] Intestinal Microbiome*[text word].