JOIN USShem Davies - of Bridgend, Wales - was also 14 when he became a father for the first time, The Sun reported.
His schoolgirl daughter Tia now has had a girl before her 15th birthday, it said.
Davies - who split with Tia's mother Kelly three months after she was born - said he was "absolutely delighted" at the news.
Davies was "shocked" when his daughter told him she was pregnant by her 15-year-old boyfriend.
He also has a nine-month-old son with new girlfriend Robyn Thomas."One minute Tia's a baby, the next she's pregnant. I could have yelled at her, but what's the point? I know how hard it's going to be for them because I was in their shoes at the same age. I didn't handle it very well when I became a dad at 14. I wasn't able to cope with it and I ran away," he said.
Tia's mother Kelly said: "My worst nightmare has always been that Tia would repeat my mistake and get pregnant young. I always lectured her about contraception."