Macbeth, impotent and therefore childless

[Oenomaus]

Lady Macbeth has born children. The only way MacDuff can explain the enormity of Macbeth's crime in killing his wife and children is to say of Macbeth, "He has no children." If the Weird Sisters have prophesied that Banquo's issue will be kings it implies that Macbeth will not have children. I think the play more than just hints at Macbeth's inability to have children. Macbeth is called "infirm of purpose" by his wife and fate has placed "a barren scepter" in his grip. Unable to have children he murders them.

[Gladys]

Lady Macbeth has born children.

You mean Lady Macduff?

[Oenomaus]

You mean Lady Macduff?

No, I meant Lady Macbeth. The play tells us that she has born children ("I have given suck") while also telling us that Macbeth has no children.

[mturbino]

What evidence is there to support this sexual interpretation of the play?

There's an essay online offering evidence to support this: "The Servant to Defect": Macbeth, Impotence and the Body Politic. You can find the essay by googling it.