Paracetamol use during pregnancy has been linked with an increased risk of multiple behavioural problems in children, according to new research.
A UK study published in the JAMA Paediatrics journal overnight claims the implications are "important for public health advice" which currently considers paracetamol safe to use during pregnancy.
But New Zealand experts are warning against alarm.
For the study, mothers from Bristol in England were asked at 18 and 32 weeks of pregnancy if they had used acetaminophen, or paracetamol, in the previous 3 months.
Five percent of the mothers reported behavioural difficulties in their children at age seven. It also found a greater risk of these difficulties if paracetamol was taken during the third trimester.
It's not the first study of its kind and draws similar conclusions to a New Zealand study in 2014.
Dr John Thompson from Auckland University led that study says while the results are similar, there's still no understanding of the mechanisms.
"By not understanding the mechanism I mean that the increased risk appears to be real...but we don't yet know what it is about taking paracetamol that increases the risk."
MedSafe reviewed a similar Danish study from 2014 - and acting group manager Chris James says all three studies have limitations.
"This included not collating the reasons for use of paracetamol, and not collecting data on dose or duration of use."
Its advice is that paracetamol should be used at the lowest effective dose for the shortest possible duration, and only if the expected benefits to the mother are considered to be greater than the risk to the mother and developing baby.
"This means that the risk of not treating fever or pain during pregnancy should be carefully weighed against the risk of potential harm of paracetamol to the mother and developing baby."
One mother Newshub spoke to says she would only be concerned if warnings about paracetamol came from the DHB or her GP.
"There's so much information out there it's hard to know what's legit," says Rachel Pahuleu.
But Ms Pahuleu only took paracetamol once during her second pregnancy and not at all during her first pregnancy.
"I guess I would be concerned if I was taking it, like, on the regular. Of course you would be, and I think a lot of new mums are just hyper-sensitive to all the information that's out there."
MedSafe will be reviewing this latest study.