###HUMAN: how many patients had a diagnosis short title preterm nec 2000-2499g and ih as the drug route?, ###ASSISTANT: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE diagnoses.short_title = "Preterm NEC 2000-2499g" AND prescriptions.route = "IH"