Pregnant girlfriend gone OCD?

My girlfriend, who is about 11 weeks pregnant, was always a bit of a compulsive neat-freak before, as am I, and it's one of her many quirks that I love. But lately she's been going in manic overdrive and stressing about everything. I realize that pregnant women are allowed to act a bit crazier than normal but it's actually starting to worry me. She'll wake up in the dead of night and do dishes, drop what she's doing to sweep or vacuum an entire floor because of a single crumb, or rearrange the whole room because somethings ascew. I hate seeing her so stressed and I know it's not good for the baby. She never wants my help with anything and insists on taking care of me while all this is going on her. I want her to rest and take it easy. I want to take care of HER. Every time I tell her this she insists that I work too hard and should be taking it easy. She says she's fine, but I can see the stress taking toll. How can I convince her that even after the hardest day of back-breaking and soul-destroying work all I want to do is come home and tend to her every need?