"It's been a while since I've been on FB(facebook) and I thought I'd drop by to let you all in on some exciting news. Honor is going to be a Big Sister, " she said in her post.
"Cash and I are thrilled and wanted to share the news directly with you so you didn't hear about it somewhere else. I appreciated all of the love and support you all gave me during my first pregnancy and will definitely appreciate it again this time around. Have a great day!"
Alba, who married Warren in May 2008 recently revealed that motherhood has made her a "little more wild".
"Oddly, I think I'm a little more wild and free since I had Honor because once she's in bed all my mum friends come over and we have dance parties at my house, " she said.
"It's really dorky and I probably wouldn't have done that before. But no, I don't go out. I hang out with my friends and I'm pretty chilled."
