I am a rare case and got HFMD as an adult 7 years ago and my doctor said I was the first case he's seen it on an adult. I guess I just wanted to be a bit different. I feel sorry when children get it, as its not the most comfortable thing in the world to deal with and for me, made walking painful for a while. According to the NHS website they isn't any risk to the baby, even if the mum catches it. There is a slightly raised chance of a miscarriage, but they aren't 100% sure as there isn't enough people getting it I guess. Or at late stages it can be passed to your baby during delivery. However, if you keep hygiene up a bit extract until its run its course, so separate towels for him to you, washing his hands regularly, baby wipes are brilliant during this time as they can be chucked away. If he's in nappies you may want to take extra caution when changing him and use gloves if possible since its passed in stools and coughing, just to be on the safe side and always wash your hands afterwards.
So I think you'll be fine, just kick hygiene up that extra bit.