First of all if you dr recommends something you don't agree with you probably should get a second opinion from another dr and not a public online forum. JMHO. That being said chicken pox is dangerous in pregnancy and can cause complications in the mother (pneumonia for starters) as well as in the fetus. I absolutely would take what the dr prescribe me since it is treatment for chicken pox in pregnancy.
You should definitely do some research this is not the best place to seek out medical device. Every woman's body is different