Corrected Gestational Age (CGA) or Corrected Age (CA) is the age of a baby born preterm that accounts for its prematurity. It is calculated by subtracting the number of weeks a baby was born preterm from their actual age in weeks.

For example: 
For a 20-week-old baby who was born 8 weeks preterm, their CA or CGA = actual age of the baby in weeks – number of weeks that baby was born preterm = 20 – 8 = 12 weeks = 3 months.

Meaning that even though this baby’s actual age is 16 weeks (5 months) old, their Corrected Age is weeks (3 months) old. 

Corrected Age/Corrected Gestational age is used in the first years of life to better track growth and developmental milestones of babies born preterm. 

For more examples, visit this website.