Generally the infected site is the issue. If it is in an open wound then all practices relating to the wound would need to be scrupulously clean but other wise there should be little issue. Do you know where the infection is?
It is definitely not being OTT to be concerned especially regarding your baby as MRSA can be so tricky to manage. I would start a dialogue about it now whilst you can gather accurate info and form a game plan on how to deal with it rather than once baby arrives.