Blake Lively reportedly kept her pregnancy a secret for a long time.

The 26-year-old actress, who is expecting her first child with husband Ryan Reynolds, decided to hold off on announcing the news until she was well past her first trimester, as they had allegedly been trying to conceive for some time.

A source said: ''She's far along.''

The blonde beauty showed off a sizable baby bump when she announced the news by posting a picture of herself cradling her growing belly on her lifestyle website Preserve.us on Monday (06.10.14).

Meanwhile, the former 'Gossip Girl' star is eager to find out the sex of their unborn baby as she wants to start decorating their nursery.

The insider told Us Weekly: ''They're going to find out the gender.

''Blake already has ideas for the baby's room.''

The 'Savages' actress previously predicted Ryan, 37, was going to be an amazing father.

She said: ''He's going to be a great father and leader and patriarch.''

The couple have never gone a week without seeing each other, and a friend close to Ryan said: ''When we're planning Ryan's trips, Black is always involved and vice versa.''