Introduction

Abstract

There is an important concept that professionals in oncology must have in mind when we talk about pharmacology in neonates and infants: In this book, as in most references about neonates and infants, the word “neonate” refers to a baby up to 28 days after birth [3]. If a neonate is born prematurely, he can still be called by this terminology—neonate—if he was born more than 28 days previously but his postmenstrual age is ≤42–46 weeks. A baby who was born more than 28 days previously is called an infant. A premature neonate is a baby who was born at <37 weeks of gestational age, and a term neonate is a baby who was born between 37 weeks and 41 weeks plus 6 days of gestational age. When an infant is more than 1 year old, he starts to be called a child. The postmenstrual age is the gestational age plus the postnatal age. The gestational age is the number of weeks from the first day of the mother’s last menstrual period until the baby’s birth, and the postnatal age is the time until birth [4] (Table 1.1).