Save the tick, it can be tested. No need to panic, though. But be aware if you have any symptoms such as fever, joint pain, or skin symptoms over the next few weeks and let your doctor know. (Not everyone gets the standard "bull's eye" rash with Lyme disease) There's no need to take antibiotics unless you have signs of infection. Even on the possibility that the tick carries a disease, it would have needed to be attached for close to 24 hrs before having the possibility of transmitting it to you.
As an aside, I was trying to find info a while back about Lyme infection during pregnancy, and there are very few documented cases of any complications related to it- that's when someone didn't even get treatment for it. And if you do need antibiotics, your doctor will be able to guide you there, but there does not seem to be any complications with pregnancy in that case, either. Just take some sort of a probiotic or plenty of yogurt rich in probiotic cultures to re-establish your intestines.