Ranitidine is just the generic form of Zantac and I am on the same thing, also 150mg, and it is considered
safe during pregnancy. I believe my doctor said it was like a Class B (for pregnancy) which is one of the safer things to use, anything below Class A or B is considered a little less safe, if I understood him correctly lol. Hope it helps you, I know it's helped me with my acid reflux.