Last month, the How I Met Your Mother actress, 38, was among the many Hollywood moms congratulating (via Twitter) Jessica Simpson on the birth of her daughter Maxwell Drew. Joked Hannigan: "Does this mean I now have the biggest bump?" (The star also cracked that people assumed she was "ready to pop" as early as April.)
The Buffy the Vampire Slayer alum wed Denisof, 46 (who starred on Buffy spinoff Angel) in October 2003.
"[Being a mother] has changed me in every way because my life is so much greater," Hannigan told Us in May 2010. "It filled a void I never knew was there -- it's the most amazing experience of my life. I just feel so blessed to get to be on this journey, to be a mommy. [Satyana] is just the greatest baby.