Photos of a pregnant Hanson were posted on Facebook, according to the magazine, with baby gifts surrounding the 21-year-old nursing student. The family had no comment.
Palin, 22, married his high school sweetheart in May outside of their hometown of Wasilla, Alaska. Hanson attends the University of Alaska, where her husband plans to enroll after the commercial fishing season.
This isn't the first grandchild for the 47-year-old 2008 Republican vice presidential hopeful. Daughter Bristol is mom to Tripp, 2.