Final answer:
Babies that are either full term or preterm with a birth weight below the expected for their age are called small for date infants. These infants may face greater health risks shortly after birth and potential growth and development challenges throughout early childhood.
Step-by-step explanation:
When babies are either full term or preterm and their birth weight is below normal for their gestational age, they are called small for date infants. This term indicates that the baby's birth weight is lower than what is expected for the length of the pregnancy. A normal birth weight for a full-term infant is typically around 3.4 kg (7.5 lb), and any infant weighing less than 2.5 kg (5.5 lb) at birth is considered to have a low birth weight.
Fetuses that did not grow adequately before birth may end up being small for gestational age, even if they are born at full term. In cases where babies are born prematurely, they may also have lower birth weights because they have had a shorter period of prenatal growth. Both scenarios can have significant health implications, increasing the risk of infant mortality and impacting growth and developmental milestones later in life.