INDIANAPOLIS (AP) – Two premature infants died after receiving adult doses of a blood thinner, a hospital said Sunday, blaming the incident on human error.

Four other infants in the Newborn Intensive Care Unit of Methodist Hospital also received adult doses of Heparin, and one might need surgery, said Sam Odle, chief executive of Methodist and Indiana University Hospitals. The other three were in serious condition.

Two babies born at 25 and 26 weeks’ gestation died Saturday night, Odle said.

Both were born in the last week, officials said. A full-term pregnancy lasts 38 to 42 weeks.

“These are very, very small babies,” Odle said. “We are confident that no other infants except for the six were affected.”

Heparin is routinely used in premature infants to prevent blood clots that could clog intravenous drug tubes, said Dr. James Lemons, a neonatologist at Riley Hospital for Children.

An overdose could cause severe internal bleeding, he said.

Hospital officials had met with family members, Odle said, adding: “Our hearts go out to the families.”

But apologies did not satisfy Whitney Alexander, mother of one of the infants who died.

“They may apologize but it didn’t help,” she told WTHR-TV in Indianapolis. “It didn’t help, because I feel like whoever the nurse was on call, they should know what they were doing and how much my baby should have.”

The hospital was investigating how the error occurred and reviewing its drug-handling procedures. Some corrective steps had already been taken, Odle said.

“This was human error – that’s all,” Odle said.

The drug arrives at the hospital in premeasured vials and is placed in a computerized drug cabinet by pharmacy technicians, Odle said. When nurses need to administer the drug, they retrieve it from a specific drawer, which then relocks.

Somehow, the adult doses were placed in the drug cabinet in the Newborn Intensive Care Unit, Odle said. There was no evidence that infant doses were given to any adult patients.

The adult and infant doses are similarly packaged, Odle said, adding that the hospital will ask the manufacturer to make the packaging more distinct.

Autopsies were to be performed Monday.

Babies born before the completion of week 37 are considered premature. Those born before 32 weeks face the greatest risk of death – about one-fifth don’t survive a year – and disabilities including cerebral palsy and retardation.

AP-ES-09-17-06 2005EDT