The girl smokes 20 cigarettes a day despite being eight months' pregnant. She conceived aged 11 when she lost her virginity to a boy of 15 on a drunken night out with friends.
The 15-year-old has since been charged with rape by police, and is due to appear again at Edinburgh sheriff court on July 10.
Her 34-year-old mother, who gave birth to her youngest child eight months ago, said she was 'proud' of her daughter.
She will be 12 years and 8 months when she has the child next month. Jenny Teague, Britain's youngest mother until now, was a month older when she gave birth in 1997
The girl, who has shoulder-length dark hair, began smoking at nine and started drinking tonic wine and vodka cocktails at ten. She claimed her cigarette habit was not harming the health of her unborn child.
She said: "I can give up smoking at any time, but I don't find it affects my pregnancy."
The girl, whose parents split up several years ago, said she would like a baby boy - and may call him Leo.
She is currently being educated at a local community centre but knows she must return to school.
'Proud of my daughter'
Her mum said: "I'm not ashamed of my daughter at all - in fact, I'm proud of her for keeping the baby.
"I know she's worried what other people will say but she can walk out there with her head held high.
"At first I wasn't too happy about becoming a gran. But now I'm used to the idea. I'm really looking forward to having another baby in the house."
When i first heard about this i was totally shocked, more at the fact that the mother is proud of her daughter?
soo any opinions on this please? Who do you blame? The parents? Education? i find in these cases more and more often the parents get blamed for everything? yes they can tell there child right and wrong but are they listning? they make there own decisions after all right?
Well i would love to hear all of your opinions please
