Hi,
Birthmarks can be very varied in nature. Response to treatment will hinge on the proper identification of your birthmark.
For example:
Nevus of Ota: almost complete removal after multiple laser treatments
Port wine stain: significant response after multiple laser treatments
Cafe-au-lait macules: variable response. Some respond well. Some don’t.
Becker’s nevus: poor response
Do see your doctor for a proper assessment or perhaps post a photo of your birthmark for more precise response.
Hope this helps!