Microblading is a form of semi-permanent makeup and tattooing. And as it stands, It is not safe to undergo any form of tattoo while you are breastfeeding.
The reason is that while any tattooing process creates some risk of infection, the concern lies heavily on the potential for passing bacteria from the microblading process to your breast milk and then on to your baby. And because there’s still very little research regarding this, it’s recommended that pregnant and breastfeeding women wait until after breastfeeding to get their brows microbladed. This way risks would be reduced to zero.