When tattoo ink is shattered via laser energy, it is possible for those tiny ink particles to enter the blood stream. Because many tattoo inks contain heavy metals it is believed those metals can be harmful to the fetus. Through there is not much evidence of the risks, it is best to err on the side of caution. Laser tattoo removal while breastfeeding is also not recommended as shattered tattoo ink particles could enter the mother’s milk supply.
The good news is that if you have begun treatment then discover you are pregnant, you can postpone treatment until after you deliver or finish breastfeeding. You won’t lose any ground. Also as long as there is ink in the skin that is small enough for the immune system to remove, it will continue to do so though the majority of the removal occurs in the first 4-8 weeks after treatment.