Rhiannon Davies launched her campaign following the avoidable death of her daughter Kate while in the care of Shrewsbury & Telford Hospital NHS Trust (SaTH).
She said the experiences of staff were vital in ensuring safe services for the future.
Maternity expert Donna Ockenden, who has been carrying out the Independent Review into Maternity Services at SaTH, has said they wanted to hear from staff – both past and present.
The review was ordered after Rhiannon Davies and Richard Stanton, whose daughter Kate died shortly after birth in Ludlow in 2009, and Kayleigh and Colin Griffiths from Myddle, who lost their daughter Pippa shortly after she was born in 2016, wrote to the then Health Secretary, Jeremy Hunt outlining their concerns about the trust.
Rhiannon Davies said today: "It is very important to state that it [the call for staff responses] is anonymous and it is all about building up a picture of what was known and what was not acted on so that the Ockenden review can present as full a picture as possible to increase the standards of maternity care and safety.
"Whatever anyone has to say is critical, and because they are protected by anonymity there is no reason not to speak out.
"The fact is this health trust's services have grotesquely let families down and we need these people to speak out and positively frame the future of maternity services."
The first part of the inquiry's review – published in December and focussing on 250 cases – revealed shocking failings in the care of women and their babies.
The second part of the review is expected to be published later this year.
Staff and former staff who wish to participate in this stage of the review or have any questions can email email@example.com in confidence.
Those who do will be sent an anonymised confidential questionnaire survey to complete.
The Ockenden Inquiry published its initial report in December, which identified 27 local actions needed to improve maternity services, as well as seven recommended for across England.
Findings outlined grieving mothers being blamed for their loss and 'missed opportunities' to prevent serious harm.