Question: What is the definition of low birth weight?
Disambiguated questions and answers: question: What is the definition of a low birth weight baby?
What is the definition of very low birth weight?
What is the definition of extremely low birth weight?
answer: infant under 2,499 g
infant under 1500 g
infant under 1000 g
Natural Questions answer: 2,499 g or less (from the Wikipedia article "Low birth weight")