Beverley Allitt, the nurse given 13 life sentences for murdering and attacking children in her care, has applied for a review of her sentence.
Allitt is serving 13 life sentences at Rampton in Nottinghamshire
Allitt, detained at Rampton High Security Hospital, Notts, was jailed in 1993 and was told she would serve a minimum tariff of 40 years.
Allitt was found guilty of four murders and attacks on nine other children at Grantham and Kesteven Hospital.
The Probation Service has written to victims' families about the process.
The letters state that although offenders are entitled to apply for a sentence review, it is not envisaged that many of the exisiting tariffs will be reduced.
This is the first time Allitt's 40-year minimum tariff has been made public.
Allitt suffered from a personality disorder when she carried out the attacks between 1991 and 1993.
She was described as suffering Munchausen Syndrome by Proxy, a condition identified by paediatrician Sir Roy Meadow in 1977.
He described it as a form of child abuse in which carers deliberately induced or falsely reported illnesses in children in order to draw attention to themselves.