I’m currently working on a whole line of pregnancy-safe and lactation-safe formulas. In the mean time….listen to HerbalMama. Good advice there.
Certainly don’t take any herbs with berberine (Oregon grape, barberry, goldenseal, coptis, etc…) in them while nursing. They can cause brain damage in the little rascal.
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.