<qa>  What is the purpose of the study?The purpose of this study is to investigate how acetaminophen APAP is released into the urine and blood; to determine how the blood levels of acetaminophen and its breakdown products affect the preterm infants health; to decrease adverse drug reactions; and to collect data on how the genetic make-up or characteristics affect how APAP is handled within the preterm infant. By taking several blood and urine samples during the study, we will be able to check the blood levels called pharmacokinetics of APAP in preterm babies. 