Double Olympic champion Mo Farah is the father of twin girls.
Farah won the men's 5000m and 10,000m amid joyous scenes at the Olympic Stadium three weeks ago and dedicated his medals to his unborn daughters.
His wife Tania joined him on the track after he achieved the rare double.
In Birmingham on Saturday, Farah said:
"My wife has been holding on so long and it's great that she held on this long and didn't give birth on the track (at the Olympics)."
He said he was present when she gave birth in London on Friday.
Farah also said his stepdaughter Rihanna was "very excited" by the arrival of her sisters.
While no names had been picked, he said they would eventually be inscribed on his gold medals.
Born in Somalia, Farah, 29, spent most of his early life in Djibouti and arrived in London when he was eight.