"I can’t make hubby sleep on the sofa because the living room is the walk way through to the kitchen so he’d have no privacy. "
"Am I being unreasonable expecting someone to give up a bed for me? I would never ask at any other time in my life, it’s just one weekend during my pregnancy."
You are being unreasonable.
You are not "expecting someone to give up a bed for me", for starters, and it's disingenuous to pretend that. You are expecting one of your sisters to give up their bed for your husband, because you consider him incapable of sleeping on the sofa.
"he’s a guest in that house so I don’t feel it’s right for him not to have the privacy, he’s not refused, he doesn’t even know the situation. I want him to feel comfortable in the family home that’s all"
He is also a husband to one of the daughters of that house and therefore family.
"I think my frustration stems from the fact that id give up my bed for my sisters without hesitation! "
Since you're not being asked to do so, we'll never know if you would.
"He hasnt refused, not at all, I’ve made that decision for him. I refuse to let a guest, in the family home, sleep on the sofa."
Is it really your place to make this decision for him? Is he not a functional adult?
"yes to some people this seems like I’m being difficult but making guests feel welcome is so important to me, I won’t argue it anymore."
I am obviously one of the 'some people' - I think you're being difficult for a spurious reason.
"i think it’s my issue of wanting a guest (in this case my husband) to have a private room to sleep in. "
At last! Yes, this is YOUR issue. And you don't get to make it your sisters' or your parents issue.
Just sleep on the damned sofa, Derek!