The 26-year-old revealed her pregnancy by posting a candid photo of her baby jump onto her lifestyle website, Preserve.
The photo- which was taken by Blake’s brother- shows the actress cradling her baby bump as she congratulates other expectant mothers.
According to a source, Blake and husband Ryan Reynolds, 37, had been trying to conceive for ‘some time’ following their 2012 South Carolina wedding.
Blake Lively announced her pregnancy last week
The insider told a US magazine: “She's far along.”
They also revealed that the Gossip Girl star is looking forward to finding out the sex of her unborn child since she has some MAJOR plans for the baby’s nursery.
They said: ''They're going to find out the gender.
''Blake already has ideas for the baby's room.''