After months of speculation and tons of baggy clothes, Justin Timberlake celebrated his 34th birthday by finally confirming that he and wife Jessica Biel are expecting their first child together.

"Thank you EVERYONE for the Bday wishes! This year, I'm getting the GREATEST GIFT EVER. CAN'T WAIT," he wrote Saturday on Instagram alongside an image of himself kissing his wife's sizeable belly. "#BoyOrGirl #YouNeverKnow #WeDontEvenKnow #WeAreTakingBets," he added.

View photos Jessica Biel and Justin Timberlake in October (FameFlynet) More

Biel, 32, has been known for her chic sense of style that shows off her killer bod for ages, so when she started wearing loose-fitting clothing several months ago, tabloid speculation about the couple, who were married in October 2012, reached new heights. Of course, some paparazzi images of the actress have shown hints of a bump — we even have a whole slideshow of them — but the pair remained mum.

Way back in October, Biel's pal and InStyle editor Ariel Foxman congratulated the couple on Instagram, though he quickly took it down. In December, Timberlake's 'N Sync bandmate Joey Fatone spilled the beans even further. "He told me a while ago, and I kept my mouth shut," Fatone was quoted as telling InTouch. "But now I can talk about it!"

"Jessica is awesome, and Justin is a kid at heart," he added when asked about the parents-to-be. "[They'll have] fun."

In other words, there really was very little question that the Timberlake family was growing… but that doesn't make Justin's pic any less exciting. Now that we've seen that beautiful bump, we can't wait to see the couple's little mini.