I really feel you on this, the itchy scalp during pregnancy is so uncomfortable and it's hard to know what's safe to use. I used a gentle, fragrance-free shampoo meant for sensitive scalps during my pregnancy and it helped quite a bit, but honestly for something like medicated anti-dandruff shampoo it might be good to just check with your gynae or PD first, since some active ingredients may not be recommended during pregnancy. They can point you to something safe for your stage, so you don't have to worry while you use it.