What is a premature infant defined as?

A premature infant is defined as one that is born before 37 weeks of gestation. The normal gestational period for a full-term pregnancy usually ranges from 39 to 41 weeks. Therefore, any birth that occurs before 37 weeks is classified as preterm. Premature infants may face various health challenges due to their early arrival, as their organs and systems may not be fully developed, which can lead to complications such as difficulties with breathing, feeding, and temperature regulation.

The other definitions provided in the options do not align with the medical standards for defining prematurity. For instance, being born after 42 weeks indicates a prolonged pregnancy rather than prematurity. A birth at exactly 40 weeks corresponds to a full-term infant. Births that occur between 37 and 39 weeks are often considered early term rather than preterm. Thus, the defining characteristic of a premature infant is their birth occurring before the 37-week mark.