The investigation – Operation Lincoln – was launched in June last year to look at whether there is a criminal case to answer over incidents where babies and mothers either died, or were injured, while in the care of Shrewsbury & Telford Hospital NHS Trust (SaTH).
It was launched after a separate inquiry into the care at SaTH, run by midwifery expert Donna Ockenden, identified nearly 2,000 cases of poor care to be examined.
The first stage of Ms Ockenden's inquiry, which was published last year, focused on the experiences of 250 families, outlining a succession of harrowing findings and leading to recommendations for changes to maternity care across the country, as well as specifically at SaTH.
The second part of the inquiry, focusing on the cases not included in the first stage, is expected to be published later this year.
West Mercia Police has now confirmed it is taking on additional staff to carry out the work required for the criminal investigation.
It is advertising for three full time 'Investigative Support Officers' to work on Operation Lincoln.
Earlier this year it was revealed that the Home Office was providing £4 million for the investigation, along with £650,000 from the Police and Crime Commissioner's office
West Mercia Police say the three new roles will largely involve "data input onto the Home Office Large Major Enquiry System (HOLMES)", and are set for a term of six months.
The police force has set up a dedicated web page for the investigation which says it is looking at "the care of mothers and babies who died or suffered serious harm in a maternity care setting at the Shrewsbury and Telford NHS Trust between October 1, 2003 and the present day".
The advert for the roles, which can be based in Shrewsbury or Worcester, states: "An opportunity has arisen for the role of Investigative Support Officer (ISO) on Operation Lincoln, the investigation into standards of maternity care at Shrewsbury and Telford Hospitals NHS Trust."
It adds: "The role primarily involves data input on to the Home Office Large Major Enquiry System and full training and support will be provided."