The discovery of inaccurate volume markings on baby bottles could save several infants from the serious side effects of having over-concentrated formula, says Plunket.

Parents of babies are being urged to check volume markings on bottles after a Consumer Affairs survey found several types of bottles being sold in New Zealand were inaccurate.

Feeding babies over-concentrated formula could cause vomiting, diarrhoea, constipation and untreated it can lead to serious dehydration.

Over time, the excess calories, could lead to children becoming overweight or obese and could harm organs such as the kidneys, said Ministry of Health child and youth health chief advisor Dr Pat Tuohy.


The survey findings could help save many children from potential side effects, said Plunket clinical adviser Allison Jamieson.

"I think it's great because it means that infants that are bottle fed are going to get what they're supposed to get if the bottle that's being used for them has inaccurate markings."

"We don't babies who are having too many calories and we don't want babies who aren't having enough," she said.

Plunket was involved in developing guidelines for caregivers who bottle feed their children and staff have been alerted to pass on the information to affected parents.

"I think people themselves will not even have the remotest idea that this is an issue."

Consumer Affairs, part of the Ministry of Business, Innovation and Employment, was alerted to the inaccurate measures as part of regular product inspection work.

Fifteen of 35 bottles surveyed were then found to have inaccurate markings by more than 5 per cent. These bottles tended to be purchased from discount shops and were mostly unbranded bottles.

Bottles that meet the European regulatory standard (the EN14350 standard) have accurate volume measures, and these tend be more expensive than other bottles, said Dr Tuohy.

He advised caregivers using infant formula for their child to only buy branded bottles which comply with the EN 14350 standard.

Those wanting to use existing bottles can have them checked at their local pharmacy which has accurate measuring equipment.