In Macbeth, when the eponymous hero is hesitating to kill Duncan, Lady Macbeth urges him forward to the murder. She memorably says:
I have given suck, and know
How tender 'tis to love the babe that milks me:
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out, had I so sworn as you
Have done to this. (I.vii.54–59)
Since she has suckled a baby, it strongly indicates that she has given birth at some point and is therefore a mother.
It is possible, of course, that Lady Macbeth has been merely a wet nurse for someone else's baby. As the Wikipedia article on "Wet nurse" makes clear, a baby's suckling can elicit lactation in a woman even if she is not herself a mother. But for two reasons, I think it is more probable that she has had a child:
- The same Wikipedia article explains that breastfeeding was not considered fashionable among the upper classes, and that wet nurses were relatively inexpensive to hire. Since Lady Macbeth is nobility, it does not seem very likely that she would have ever worked as a wet nurse.
- Admittedly, even members of the nobility could fall on hard times, so I suppose it's possible that Lady Macbeth needed the money. However, her personality does not seem like a good fit for the job of wet nurse, and I imagine she would have had difficulty getting hired.
On the other hand, the quoted speech does say "the babe that milks me", not "my babe", so it's of course possible that the baby being suckled was not Lady Macbeth's own. It is plausible that perhaps Macbeth's first wife had died in childbirth and Lady Macbeth was the hired wet nurse, whom he subsequently fell in love with and married. That would make the suckling baby Lady Macbeth's stepson. Perhaps Shakespeare was merely using the unfair stereotype of the wicked stepmother in portraying Lady Macbeth's willingness to kill the baby she was suckling.
The rest of the play does not mention the Macbeths' children anywhere that I recall. Banquo's son Fleance, Macduff's son, and old Siward's son are all onstage at various points, but we do not hear any more about the child or children Lady Macbeth has suckled. Perhaps this is a clue that the Macbeths themselves had no children, but Lady Macbeth had been a wet-nurse at some point.
Another possibility that Macbeth is her second husband. Perhaps the child she is referring to was one by her first husband.
So: how many children had Lady Macbeth?
- Zero, because she had been only a wet-nurse?
- One, because her speech refers just to one baby, in the singular?
And if the answer is nonzero, are the children Macbeth's or from a previous relationship? It would be good if the answer gave evidence by quoting the play. But I'll settle for secondary sources or even wild speculation if that's all that's on offer.
In researching this question, I did look at L.C. Knights's 1933 essay called "How Many Children Had Lady Macbeth?", but although I was very excited to find it, I was quite disappointed because the title is misleading and he does not answer the question at all.