Hello ma am and welcome. Chills during pregnancy have been commonly encountered and found to be mainly due to exhaustion or anxiety during pregnancy. But if seen more often, with short or no gaps, and lasting for longer periods of time, infections should be suspected and carefully ruled out. You have not mentioned the gap between your episodes of chills, so it is indeed difficult to pin point the cause, but I am assuming they are due to exhaustion or anxiety, until your doctor can confirm or rule out the same. Hope this helps. Best wishes.