The research is quite limited on the impact of laser services while breastfeeding / chestfeeding. However, the consensus from both the medical community and laser providers would be that a person can proceed with cosmetic laser services (i.e. laser hair removal and skin care treatments) while breastfeeding / chestfeeding, but avoiding treatment on or around the areola and breast tissue. Some people choose to be a bit more cautious and opt to postpone laser hair removal in the underarm areas as well, since the armpit is anatomically near milk producing glandular tissue.
As with pregnancy, it is also helpful to consider that hormones can still be affecting hair growth patterns. It is not uncommon for people to experience hair loss postpartum.
It would also be important to consider that some lasers require the use of a topical numbing cream and one should check with their medical provider prior to using to ensure that use of numbing cream would not be an issue with desired treatment zones and feeding their baby.