Make a tune to help her remember. You can also use a familiar tune. For example, sing to the tune of "London Bridge": "Amy's birthday is in August, is in August, is in August. Amy's birthday is in August, on the seventh day."
Devise a mnemonic. You can use a familiar nursery rhyme to help you think of one. For example, "Jacob had a little November whose fleece was white as thirteen snowflakes" or, "Carly be nimble. Carly be quick. Carly was born on April 5th."
Utilize repetition to help him remember his birthday. Ask your child when his birthday is when on car rides, walks or at bed time. The more he repeats it, the more likely he is to remember it.
Display the child's birthday. Hang a sign in her room that says, "My birthday is February 5th." Alternatively, put her birthday -- and everyone else's birthday in the family -- on a birthday chart. Place it on the refrigerator for everyone to see and keep track of birthdays.