"We feel so lucky to have been able to experience the miracle of birth once again and are forever grateful for the opportunity to be the parents of another little angel," Bundchen wrote. "Vivian Lake was born at home on December 5. She is healthy and full of life. Thank you all for your support and well wishes. We wish you and your families many blessings."
Bundchen and Brady already have a 2-year-old son, Benjamin, and Brady has a third child -- 5-year-old John -- with actress Bridget Moynahan.
The 35-year-old Brady, who is hesitant to talk about personal matters, didn't mention the birth at his Wednesday news conference, though he acknowledged recently that it would come soon. He was present at the Patriots' walkthrough practice on Wednesday and was on the field Thursday as well.
The Patriots face the Houston Texans on Monday night in a matchup of two of the best teams in the AFC.