In March, a friend revealed that the new arrival is team pink, saying: “Uma is having a baby girl. She's happy and just a few months along right now. She's due in late summer.”
Uma, 42, already has two children - ten-year-old son Levon and daughter Maya, 13 with her second husband Ethan Hawke.
She was previously married to British Oscar nominee Gary Oldman.
Meanwhile Arpad is a daddy-of-two. He had Arpad Flynn Alexander Busson and Aurelius Cy Andrea Busson with former girlfriend, Australian model Elle Macpherson.
The French-born businessman has been dating Uma since 2007. They split briefly in 2009 but rekindled their relationship last year.
He made his fortune in the world of hedge funds and when pressed on how much he's worth quips "enough", "enough" estimated to be in the region of £136 million.
Uma recently told Harper's Bazaar how contented she is in her current relationship: "I have something I would really like to express about my love life," she said.
"I'm happier with it now than I've been in many, many years. Yes I'm trying to have as peaceful a personal life as possible."
Über-mum Uma Thurman expecting with multi-millionaire beau
Cheryl is the cream of the crop as she joins Cameron on the red carpet
It's a little princess!