Final answer:
An infant is considered Small for Gestational Age (SGA) when their birth weight is below the 10th percentile, regardless of head circumference and length, with the correct answer being C) Weight below the 10th percentile, regardless of head circumference and length.
Step-by-step explanation:
Infants are characterized as Small for Gestational Age (SGA) based on birth weight, head circumference, and length percentiles when they fall below the 10th percentile in weight, regardless of their head circumference and length measurements. This means that answer C) Weight below the 10th percentile, regardless of head circumference and length is the correct option. The categorization of SGA is important as it helps in identifying infants who may be at risk for certain health issues due to inadequate growth in the uterus, often related to factors such as maternal, fetal, or placental reasons. The average birth weight of a full-term infant is approximately 3.4 kg (7.5 lb), and birth weights lower than 2.5 kg (5.5 lb) are considered low and can be indicative of intrauterine growth restriction (IUGR) or pre-term birth, both of which carry higher risks of mortality and morbidity shortly after birth.