An NHS hospital trust said it was making improvements after a Care Quality Commission (CQC) report criticised maternity care standards.
A CQC inspection at Basildon University Hospital earlier this year found that women assessed as at 'high-risk' were allowed to inappropriately give birth in the midwife-led birthing unit.
Inspectors rated the hospital's maternity unit 'inadequate' because there was insufficient evidence that staff were competent to carry out their jobs.
The Trust was previously criticised following the deaths of baby Ennis Pecaku in September 2018 and mother Gabriela Pintilie in February 2019.
The unannounced inspection was carried out on 12 June 2020 after an anonymous whistle blower alerted the CQC to safety concerns at the hospital's maternity unit.
The information, together with a review of the Trust's incident reports, highlighted a cluster of six serious incidents where babies were born in poor condition and subsequently transferred out for cooling therapy during March and April 2020.
Inspectors interviewed 16 staff members, checked equipment, and reviewed 12 medical records.
Among other reasons given for rating Basildon's maternity unit as inadequate on safety grounds were that:
Staff did not always complete training in key skills
Multidisciplinary team working was dysfunctional
Consultant cover was inadequate
They also reported that the leadership team lacked the skills and abilities to run the service.
Although staff in the maternity unit were fully aware of safety concerns, the service lacked an 'open culture' where they could air their worries without fear.
Inspectors noted that the "maternity senior leadership team, managers, and staff reported a longstanding poor culture over a number of years, which had resulted in a deterioration of the safety of the service".
In one observation, inspectors noted that during a delivery suite safety handover, the anaesthetist arrived late, communication between teams was ineffective, and women were referred to by their room numbers rather than by name.
Midwives did not receive a full handover of all the activities within the delivery suite at the beginning of each shift.
Mid and South Essex NHS Foundation Trust said that inspectors had noted improvements since their last visit.
Clare Panniker, chief executive of the Trust said: "It is so important that mums feel safe when they come to us to have their babies, and that our staff feel supported to deliver the very best care. These are the two areas we've been focusing on and have taken urgent and significant action to address.
"We know that our services are safe to use, but I'm sorry that we didn’t make improvements quickly enough.
"Our dedicated staff had already begun to make changes before the CQC visited us – and the report recognises that a raft of improvements had been put in place.
"We have a new leadership team, invested £1.8million in recruiting 29 more midwives and two additional consultants, opened three more delivery beds for high-risk women and created a triage service.
"We have also overhauled our processes and training to ensure that we offer women the very best care and support and that we are addressing the issues raised by the inspectors."
The Commons Health and Social Care Committee is currently investigating recurrent failings in maternity services in England in the light of investigations that followed incidents at East Kent Hospitals University Trust and Shrewsbury and Telford Hospitals NHS Trust, as well as the inquiry into the University Hospitals of Morecambe Bay NHS Trust.
Jeremy Hunt, the Committee chair has said they were "looking at the evidence that's been gathered to date and whether recommendations are being acted upon to ensure that lasting improvements are made to safeguard the lives of mothers and their babies".