The Gossip Girl star announced her pregnancy via her own site Preserve by posting a photo of herself cradling her baby bump.
Sharing many photos of soon-to-be-mums in her latest post, Blake surprised fans by including a photo of herself and her own bump as well - confirming she too is expecting.
Already sporting a fairly big bump, it seems Blake has been keeping her pregnancy a secret for quite some time.
Alongside her photos, she wrote: "Preserve at its core is about family. Family is the single word our founder, Blake built this home on. We have something for men, for women, for the old, but we realised, we don't have anything for the new.
"With family on our mind, we looked to the origin of it all—to the women in our lives who are right there, at that special moment; at the creation of family.
"Today we celebrate them. With food to fill their tummies (as if that needs more filling), presents to soothe their tired (and swollen) soles, toys to warm their baby's souls, projects to provoke them, and decorations to inspire creativity and merriment in all.
"We had too much fun with this. Because there's so much to share, we break up our first ever Preserve Celebration into multiple parts. In the upcoming days we will bring even more treats and fun. The entire next month will be sprinkled with highlights for women in this exciting chapter of their lives.
"Congratulations to all the expecting mothers out there."
This will be the first child for Blake and husband Ryan Reynolds who married back in 2012.
Last year, actor Ryan admitted that he and Blake were looking forward to starting a family together, saying: "We'd love to have a big family. We both come from big families—my parents did four, Blake's did five. A lot of people say it's crazy, but we'll only know when we're there, you know?"
Stars who welcomed babies in 2014!
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe
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