But the happy occasion has turned tragic for the couple, following a grave mistake by hospital staff: the twins were accidentally given a major dose of the anti-coagulant heparin and are currently struggling to survive.
According to People magazine, the actor's rep, Cara Tripicchio, released the following statement: "Dennis and Kimberly appreciate everyone's thoughts and prayers and hope they can maintain their privacy at this difficult time."
The babies are currently in stable condition in the neo-natal intensive care unit at Cedars-Sinai Medical Center in Los Angeles.
The hospital did not directly comment on the Quaid twins, but it did say on Sunday that a "preventable error" occurred with three unidentified patients receiving heparin.
"I want to extend my deepest apologies to the families who were affected by this situation, and we will continue to work with them on any concerns or questions they may have," said Dr. Michael L. Langberg, chief medical officer at Cedars.
He added: "This was a preventable error, involving a failure to follow our standard policies and procedures, and there is no excuse for that to occur at Cedars-Sinai. Although it appears at this point that there was no harm to any patient, we take this situation very seriously."