Is it safe to use "head & shoulders" antidandruff shampoo&conditioner 2x a week during pregnancy? It's active ingredient is pyrithione zinc. I'm on 9wks

No known. There are no known contraindications in using shampoos containing pyrithione zinc while pregnant. Always check with your obstetrician when uncertain about medications during pregnancy.
Safe. Head and shoulders is safe to use as it has little to no absorption into the systemic blood stream. If you have a cut or open sore on your scalp, you should avoid it. You should also always discuss any medicated shampoos with your dr as well.