You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Preterm infant is defined as - and explain in detail?
Preterm is defined as babies born alive before 37 weeks of pregnancy are completed. Subcategories include- 1. Extremely preterm is less than 28 wks 2. Very preterm 28 to 32 wks 3. Moderate to late preterm 32 to 37 wks Reference Park&;s textbook of preventive and social medicine 23rd edition pg 536