Context:
In this play there is a great imbalance in gender roles: the world of Macbeth is dominated by men and the macho experience of wars and battles. There is no place for women except as mothers. Lady Macduff demonstrates the success of this role. There is a contrast between the fertility of her home and the sterility of the Macbeth household. Has Lady Macbeth had a child? Where is it now?
Notice:
'Unsex me', says Lady Macbeth, asking to join the world of men in order to commit the murder. She also gives her husband's quality of 'kindness' a feminine edge by connecting it with mother's 'milk'.