Ugh I can't stop

I just found out that I'm 4 months preggers. And for the past 6 months I've had this weird craving and I can't make it stop. I eat pinches of baking soda. It adds up to about one teaspoon a day. I love the texture it calms me down. My husband thinks I need a doctor.

Is this harming my baby? I'm not trying too I just like this baking soda