What happens if my child ages out after filing Form I-130?

In accordance with the Child Status Protection Act (CSPA),

your child’s age will “freeze” on the date you applied Form I-130 for him or her. Since it may take too much time for USCIS to approve and process I-130 petitions, your child may become older than 21 years. To avoid confusion, the CSPA was introduced.

 

Also read:
How do I find the location that I applied for an immigrant visa or adjustment of status on Form I-90?