Request the single dose flu shot. Multi-dose flu shots contain Thimerasol, a mercury based preservative. Multi-dose doesn’t mean you get more than one shot, it means it is packaged for the doctor or pharmacist to pull multiple vaccines out of the container for multiple patients and therefore requires more preservatives than the single dose which is used on you and then tossed out. I listened to a couple pod casts and read up on it. I’m very cautious about medications while pregnant, but there is a lot of scientific evidence that flus can cause serious harm to your baby, and your immune system is down while pregnant making you more susceptible.