"2 years ago today I met the man of my dreams and now we're proud to announce we're starting a family! #happybirthdaytome! @BrianGGallagher," the former Smash star tweeted.
"Yup! Working on a new project w/ @meganhilty! It's been in development for months now, & is due in September! Working title: #GallagherBaby!" Gallagher wrote.
Hilty and Gallagher learned they were expecting back in January, as Gallagher was celebrating his 34th birthday.
"We took the test together," she told Us Weekly. "It was the best present he got this year -- or any other year for that matter!"
Thank you for all of the sweet birthday/baby wishes! Now if you'll excuse me, I've got some cake to eat! pic.twitter.com/PDxtNSGI23— Megan Hilty (@meganhilty) March 29, 2014