Around 500 doctors have signed an online letter expressing concern over a coroner's findings after it was recommended for breastfeeding mothers to refrain from drinking alcohol.
The recommendation follows the death of two-month-old Sapphire Williams.
The baby had such high levels of alcohol in her blood, doctors believe her death could not possibly be linked to a single breastfeed.
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A toxicologist found the amount of alcohol in the baby's blood from her heart was 308 milligrams per 100 millilitres - six times the legal limit for an adult, according to the coroner's report.
The coroner could not establish an exact cause of death, but noted "it is more likely" the baby's high blood alcohol level resulted from alcohol consumed by the mother.
That statement is now being challenged by doctors.
"Calculations that me and my colleagues have made suggest that might not be the case," says Hei Hei Health clinical director and Christchurch GP Dr Robert Seddon-Smith.
The mother consumed 18 bourbon-and-cokes the day before her daughter's death and breastfed her on the day she died.
Dr Seddon-Smith says the baby's acute intoxication could not have occurred solely through breastfeeding.
"In order for a baby to have got enough alcohol to achieve those levels from breastfeeding... the mother would have had to have twice the deadly level of alcohol," says Dr Seddon Smith.
Another concern outlined in the letter to the coroner is the recommendation that breastfeeding mothers should not consume any alcohol "at any stage".
University of Otago toxicologist Dr Belinda Cridge says new mothers should not panic - nor do they need to refrain from drinking altogether.
"You can have a drink of wine. It's not the end of the world," Dr Cridge told Newshub.
However, she confirmed that alcohol does transfer to breast milk, and urges mothers to exercise caution and drink responsibly.
"If you are going to do it, drink right after you've breastfed so there's the longest possible time before you're feeding your baby again," she advises.
The coroner does not comment after issuing findings - but the report did note other complicating factors, such as the baby being premature and sleeping in a dangerous environment.