VIDEO : Blake Lively Congratulates Amber Tamblyn's New Baby Bump

Blake Lively's and Amber Tamblyn are about to have plenty of playdates on their hands for their little ones! Just yesterday, Tamblyn made the exciting announcement that she and husband David Cross are expecting their first child together, a baby girl, in the coming months. And now her best friend Blake Lively is weighing in on social media, congratulating her fellow Sisterhood of the Traveling Pants star on the exciting family news.