Men can be oblivious sometimes, I don't think it's on purpose. Sometimes you have to tell them exactly what you need.
If my DH were being dense in your situation, I'd day "DH, DS wants to be held, you know the doctor said I shouldn't be lifting, so you need to do it." Don't mention that you hurt, or you are tired, etc - just lay it out for him in facts, not feelings.
Men also have never been pregnant and haven't had dietary restrictions, so they sometimes forget that there is something about a monster that makes it "unacceptable". That seems like more of a slip up.