Final answer:
Gestational age is a major factor in relation to premature vs full-term birth. Pre-term birth is one of the major causes of low birth weight, which increases the risk of death shortly after birth.
Step-by-step explanation:
The major factor in relation to premature vs full-term birth is gestational age. Infants born before full term, defined as 36-40 weeks after fertilization, are usually smaller than full-term infants because they have spent less time growing in the uterus. Pre-term birth is one of the major causes of low birth weight, which increases the risk of death shortly after birth.