Turning 21 does not cancel the petition, but it can move you into a different category with a longer wait. However, the Child Status Protection Act may still protect your age depending on how long USCIS took to process the petition.

Under CSPA, the time the I-130 was pending can be subtracted from your age. Many people still qualify as under 21 for immigration purposes even after their birthday.

If your mother later becomes a US citizen, your case could move much faster. A lot of families see delays resolved that way, so it’s something to keep in mind.