A survey by the Consumer Affairs Ministry has revealed some low-cost baby feeding bottles have inaccurate markings, meaning infant formula is too concentrated and this can lead to health problems.
The ministry surveyed the volume indicator markings on 35 feeding bottles after receiving a complaint.
It found 15 bottles had markings that were inaccurate by more than 5% - most of them purchased from discount shops.
Pat Tuohy, the ministry's chief adviser of child and youth health, says that variance has health consequences. Formula that is too concentrated can cause vomiting, diarrhoea, constipation or harm organs such as the kidneys.
Dr Tuohy said parents who want to check the accuracy of their bottles' markings can take them to pharmacies which have accurate measuring equipment.
