The Transformers star and her husband Brian Austin Green secretly welcomed a baby boy, named Noah Shannon, on 27 September (12).
Announcing the news in a post on her Facebook.com page, the actress writes, "We have been very lucky to have had a peaceful few weeks at home. He (son) is healthy, happy, and perfect. We are humbled to have the opportunity to call ourselves the parents of this beautiful soul and I am forever grateful to God for allowing me to know this kind of boundless, immaculate love.
"Thanks to those of you who wish to send your positive energy and well wishes. May God bless you and your families abundantly."
The couple wed in 2010.
This is Green's second child - he already has a 10-year-old son, Kassius, with his ex Vanessa Marcil.