What is the term for a baby born before 37 weeks gestation?

The term for a baby born before 37 weeks of gestation is indeed "preterm infant."

A pregnancy is typically considered full-term when it lasts between 39 to 40 weeks. Babies born before completing 37 weeks are classified as preterm and may face various health challenges due to their early arrival. Preterm infants often require specialized medical attention as their organs and systems may not yet be fully developed, leading to complications such as respiratory distress syndrome, difficulty maintaining body temperature, and feeding challenges.

The other terms mentioned refer to different situations: a full-term infant is born between 39 and 40 weeks, a post-term infant is born after 42 weeks, and a low-birth weight infant refers to an infant weighing less than 5 pounds, 8 ounces at birth, regardless of gestational age. Therefore, the classification of a baby born before 37 weeks as a preterm infant accurately reflects the risks and care needs associated with early delivery.