Why did women slaves not work ancient fields?

As we work our way through material forTime of Troubles, we are struck by many things, such as the rampant economics imperialism of the last couple of decades, or the assumption that the ‘economy’ refers only to commercial activity and that agriculture is for some strange reason not an economic activity. But the other day, I was struck by another question: why did female slaves not tend to work the fields in ancient Greece and Rome? It may have something to do with the following assumptions,...