Heigl and her husband, 36-year-old singer/songwriter Josh Kelley, are also parents to 4-year-old daughter Adelaide, whom they adopted domestically in 2012 after adopting Naleigh from South Korea in September 2009.
Heigl revealed that her and Kelley were definitely planning on having more children in a blog post announcing her pregnancy late last month.
"We've known for a while that we wanted to add to our family and frankly didn’t really care how we chose to do that," she wrote. "We were considering adoption again, fostering, or pregnancy if possible. Seeing as I have never been pregnant and as my OB/GYN reminded me last year, I'm of advanced maternal age, I wasn't sure pregnancy was even in the cards for us. Turns out it was very much in the cards!"