Final answer:
A child born with normal birth weight and length but then falls below the 20th percentile for these measurements would be described as having c) 'Failure to thrive'. This term is used when an infant doesn't grow as expected and it may indicate issues such as undernutrition or medical conditions that need to be addressed.
Step-by-step explanation:
When a child is born with a normal birth weight and length but falls below the 20th percentile for these figures over the following months, the most accurate term to describe this baby's development is c) Failure to thrive. Failure to thrive is diagnosed when an infant does not gain weight or grow as expected over time. Unlike stunted development, which refers to children who are chronically undernourished and result in being too short for their age, failure to thrive can occur even in infants who started off with a normal birth weight and length. It can be a sign of undernutrition, inadequate feeding, or possibly underlying medical issues.
Infants generally should triple their birth weight and double their birth length by their first birthday. The growth pattern of the baby is critical over the initial months and is a fundamental marker for overall health and development. If an infant does not meet these growth expectations, intervention to investigate the cause and provide treatment is essential.