No Marriage Child Acknowledgement

my situation right now is that my girlfriend is pregnant and i am under petition to migrate to US..so i cant marry her not until i became a US citizen

my question is can i acknowledge our coming child for our baby to use my surname and be my legitimate child?? 

or is there a way to process illegitimacy to legitimacy:?: 

You can acknowledge your coming child either thru public document ( ikaw ang magprocess ng birth certificate registration- they can send the papers to the US if nandun ka na para mapirmahan mo - you can also have it notarized sa consular office ng Phils. - and send it back sa Pilipinas.) or private document -( like  your personal handwritten letter acknowledging the child etc.)

As for the legitimacy - if the only legal impediment for you and your gf to get married is your minority (below 18 yrs. old) at the time of her pregnancy - pwede ang legitimation process - meaning pag nagpakasal kayo magiging legitimate status ng anak nyo -( sa civil registrar lang ginagwa ung process).
Legitimation  is possible if neither of you nor your gf is already married.