Health officials have identified three further cases of blood poisoning that have been linked to the suspect batch - bringing the total number of cases to 21.
Public Health said that the babies, who became unwell last week or over the weekend, are responding to antibiotic treatment.
The cases were identified after analysis of clinical records of the babies, a spokeswoman said.
Questions have been raised over how a batch of intravenous fluid could potentially have become contaminated, after the death of one baby.
The suspected contaminated batch of a food supplement linked to the blood poisoning of 17 babies, was sent to 22 hospitals.