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/ Source: TODAY
By Eun Kyung Kim

Katherine Heigl is speaking out about her surprise pregnancy and what it means to her growing family.

“We are expecting a third addition to our tribe! It was totally unexpected but thrilling nonetheless,” she wrote on her lifestyle website, Heavenly Days.

The former “Grey’s Anatomy” star and her husband, singer Josh Kelley, are expecting their third child, a boy, in January. The baby will join the couple’s two daughters.

“Naleigh and Adalaide are over the moon and can not wait to spoil their new sibling rotten and of course Josh and I are full of high hopes and bubbling anticipation,” Heigl wrote.

MORE: Katherine Heigl is pregnant! Actress and Josh Kelley expecting first son

The actress noted that while the child will be the couple’s third, “the whole pregnancy is new to me.” She and her husband adopted their first two children and the actress has been vocal about her desire to adopt because she grew up with an adopted older sister.

“We’ve known for awhile that we wanted to add to our family and frankly didn’t really care how we chose to do that. We were considering adoption again, fostering, or pregnancy if possible,” she said.

She also shared the news on Twitter in a post that included a photo of herself getting an ultrasound and on Instagram, where she provided a preview of her newest addition.

Heigl, 37, said her doctor reminded her last year that she was "of advanced maternal age," so she wasn't sure if pregnancy would be an option.

"Turns out it was very much in the cards!" she said, calling the occasion "an amazingly blessed time."