Niall Horan says he was overjoyed to discover his older brother Greg Horan and his new wife Denise Kelly are expecting their first child together.
The couple told the One Direction singer the good news at their wedding on Wednesday.
Greg told The Sun newspaper: "It's Niall's first niece or nephew so he's delighted."
Niall - who was his brother's best man - started the day in style by belting out boy band Busted's hit song 'Crashed The Wedding' as the family drove to St Michael's Church in County Westmeath, Ireland.
The 19-year-old heartthrob also made time for his fans and signed a number of autographs before he entered the church with the rest of the 150-strong wedding party.
Niall took his best man duties very seriously and was allegedly rehearsing his speech for weeks before the event.
Greg told the Irish Sun before the big day: "He has been working on the speech as far as I know so we will see how that goes.
"He's my only brother - there was never any other choice for my best man than Niall."
He also revealed he had invited Niall's bandmates Zayn Malik, Liam Payne, Harry Styles and Louis Tomlinson to the nuptials, but they all declined their invitations.