The "Smash" guest star and Busson, 49, called off their engagement in 2009, but reunited last year. "Uma was definitely not planning on having another kid. It was a surprise," a source told Us, which first broke the news of Thurman's pregnancy back in February. "But she's over the moon about it, very excited."
Thurman and her daughter-to-be were feted at a small baby shower in New York on May 31, thrown by her half-sister Taya Thurman. Among the two-dozen guests at the baby pink-elephant-themed bash were Thurman's "Smash" co-stars Debra Messing and Will Chase.