Babies born at ≥37 weeks of gestation are considered to be born at term; therefore, any baby born earlier than 37 completed weeks of gestation are termed as premature babies. A consistent rise in preterm birth rate has been noted around the world (Norman et al, 2009). Available statistics from the United States shows that preterm births constituted 12.8% of live births in 2006; this is an increase by 20% since 1990 (Muglia and Katz, 2010). The challenges that result from preterm delivery will vary depending largely on the gestational age and birth weight. The general rule is that adaptation of the newborn to extra-uterine environment becomes more problematic with smaller and less mature babies. It is therefore important to understand some definitions related to the gestational age and weight.