The presenter revealed in the October issue of Good Housekeeping magazine that she's had a tumour in her pituitary gland for the past eight years, and one of the side effects is being unable to conceive.
She said: "I'm lucky that it's benign so it's not in itself a worrying thing. Sometimes it's big and makes me mad, and sometimes it's small and is in the background. Sometimes it screws up my hormones. I have various tests now to make sure the side effects aren't too onerous.
Sue added of not being able to have children: "We live in a time and place where we think everything is possible. I don't know if I would have gone on to have children. But as soon as someone says you can't have something, you want it more than anything."
She also spoke about her feelings when TV partner Mel Giedroyc became a mum, saying: "When she had her first child I thought: this is an experience I won't have or share. You've gone somewhere I can't go. You think it is going to destroy something, but actually it hasn't destroyed anything – we have very different lives and different experiences now."
The full interview appears in the October issue of Good Housekeeping, on sale 2 September. Also available in digital edition on Apple Newsstand. For further exclusive content, please go to goodhousekeeping.co.uk