Gerard had posted the happy news on Spain's Day of the Holy Innocents, which is similar to April Fool's Day. And with no official confirmation coming from representatives, or any acknowledgement on Shakira's Twitter page, it appeared the announcement was a ruse.
Writing in Spanish, the 25-year-old said: "Our son has been born! We are very happy! Thanks to all for your messages!" He posted the tweet just days after Shakira was snapped shopping for gifts in Barcelona. She is expected to give birth early next month.
The 35-year-old Grammy winner revealed in September that she and her sportsman beau were "happily awaiting the arrival of our first baby". She later revealed the new baby is a little boy.
Gerard recently revealed during a radio interview that the couple had not decided what to call their firstborn. "Concerning the name, we just haven't been able to decide," he said. "There are ridiculous names, like Ulisito, that came out of the press' need to report nonsense. There was also Biel, which we like, but I don't think it will be that one either, or Gerard. We'll see."
Shakira and Gerard have been dating for two years, and the Colombian star says he is the "best thing" that has ever happened to her. She said: "This man is the best thing that could have happened in my life. And now the baby!"
She was in a relationship with Antonio de La Rua, the son of former Argentinian President Fernando de la Rua, for more than a decade. They split in 2010.