USCIS recently confirmed with the American Immigration Lawyers Association that traveling while your advance parole document is still pending will cause it to be denied. The application now needs to be approved before you leave the United States if you want to use it to reenter the United States.
An advance parole document is obtained by filing a USCIS Form I-131. The I-131 is normally one of the Forms submitted in an Adjustment of Status (AOS) application. The Form has multiple purposes related to travel outside of the United States. An approved Advance Parole allows an immigrant to return to the United States after traveling abroad while their Adjustment of Status application is pending at USCIS. In the past, USCIS would still approve the Advance Parole if you left the United States before the Advance Parole was approved. They have recently abandoned this policy. They now point to page 6 of the latest Form I-131 instructions which states that traveling while the application is pending will cause it to be abandoned. You must have the Advance Parole approved before leaving the United States if you want to preserve your AOS application. If you have a valid H, K, L, or V visa, it is still possible to use them in many circumstances to return to the United States without the Advance Parole and still preserve your AOS application. If you don’t have any of those visas, or an approved advance parole, you should speak with your immigration lawyer before leaving the United States while your Adjustment of Status application is pending. Also note that if you are out of status and receive an advance parole, in some instances you can still be denied entry back into the United States. Again, speak with an immigration attorney if you are in this situation.