The age women start having cervical smears is to increase from 20 to 25.
The Ministry of Health says screening women between the ages of 20 and 24 does not reduce cervical cancer mortality rates.
"Since the inception of the National Cervical Screening Programme in 1990, there has been no reduction in cervical cancer incidence rates or mortality for those aged 20-24," says clinical director of the National Screening Unit, Dr Jane O'Hallahan.
"In contrast, there's been a marked and gradual reduction in cervical cancer rates in older age groups."
And there's now a strong body of evidence that early screening causes more harm than good.
"The primary reason for this is the human papillomavirus (HPV) that causes more than 90 percent of cervical cancers is common in younger age groups and typically clears up on its own," says Dr O'Hallahan.
"Harms of screening this age group includes over-diagnosis, increased stress and anxiety associated with additional tests and treatments and unnecessary colposcopy, which is associated with heightened risk of future pre-term births."
The age change comes in to force in 2018 and is in line with many other countries including Australia, England and France.
It coincides with the move to change the primary test for cervical cancer to screening for HPV every five years.
But Dunedin cytopathologist, Dr Peter Fitzgerald, believes it will lead to increased cancers in the under 30s.
"It may make a significant difference in the 25 to 30 age group. They will have their cancers detected later and the disease may be more advanced."
He admits they do carry out a lot of "unnecessary" colposcopies, but he says they "don't know which CIN 3 lesions will progress to cancer."
Lynda Williams, Auckland Women's Health Council co-ordinator, says they support the move to screen from the age of 25, but do not support the move to HPV screening every five years.
Both Dr Fitzgerald and Lynda Williams would prefer co-testing, including both HPV testing and cervical smears.