The actor's rep, Cara Tripicchio, declined to give a reason, but said in a statement: "Dennis and Kimberly appreciate everyone's thoughts and prayers and hope they can maintain their privacy at this difficult time."
Thomas Boone and Zoe Grace, who were born on Nov. 8, were accidentally given a major dose of the anti-coagulant heparin, TMZ.com reports.
The babies are in stable condition in the neo-natal intensive care unit at Cedars-Sinai Medical Center, TMZ reports.
Hospital ApologizesThe hospital did not directly comment on the Quaid twins. But it released a statement saying that on Sunday 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."
According to Langberg, three unidentified patients had their IVs flushed with an overly high concentration of heparin, used to keep IV catheters from clotting.
"As a result of a preventable error, the patients' IV catheters were flushed with heparin from vials containing a concentration of 10,000 units per milliliter instead of from vials containing a concentration of 10 units per milliliter," said Langberg. "The error was identified by Cedars-Sinai staff, who immediately performed blood tests on the patients to measure blood clotting function."
Other patients were tested as a precaution, Langberg said.
In the end, two of the patients had to be given a drug to reverse the effects of the heparin to help restore blood clotting to normal, he said.
"Additional medical tests and clinical evaluation conducted on the two patients indicated no adverse effects from the higher concentration of heparin or from the temporary abnormal clotting function," Langberg said. "Doctors continue to monitor the patients."
Quaid's twins were born via a gestational carrier – a woman who carries another couple's baby conceived by the parents' own egg and sperm.