"No, not even Mariah could plan for that," Cindi Berger told People Magazine.
Carey gave birth Saturday at a hospital in Los Angeles. The girl weighed 5 pounds, 3 ounces, and her slightly younger brother 3 ounces more.
Cannon, a judge on "America's Got Talent," took note of the anniversary in a Tweet: "My wife just gave me the most incredible anniversary gift ever in life! I won't ever be able to top this!"
Berger said she has spoken to both Carey and Cannon and described them as "overjoyed." Carey has also received congratulations from a number of celebrities, including expectant mother Alyssa Milano.