Cwm Taf maternity: Chief executive Allison Williams on sick leave

Cwm Taf's chief executive Allison Williams being questioned by AMs, with chairman Marcus Longley

The chief executive of a health board under fire for failures in maternity services is on sick leave, it has been revealed.

Cwm Taf Morgannwg's maternity services are in special measures after treatment for mothers and babies at two hospitals was called "dysfunctional".

Now Allison Williams is on an "extended period of sickness absence".

On Wednesday evening, Rhondda Cynon Taf council unanimously passed a motion urging her to consider her position.

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Cardiff and Vale deputy chief executive Sharon Hopkins will take over as Ms Williams' interim replacement.

An independent review team last autumn was called in, prompted by concerns about the deaths of a number of babies at Royal Glamorgan and Prince Charles hospitals in the south Wales valleys.

It heard women had "distressing experiences and poor care".

Ms Williams offered a public apology saying she was "deeply sorry for the failings" identified.

But there have been pressures from some quarters for senior executives to go.

In May, Rhondda Cynon Taf council leader Andrew Morgan revealed he had lost confidence in the health board months before the review was published and had called for Ms Williams to consider her position.

Then on Wednesday, the council motion to back his call was passed with cross-party support.

It also called on the health board to "carefully consider its options" in addressing the council's concerns.

An independent panel, led by Mick Giannasi, is overseeing improvements.

Dr Sharon Hopkins will take over on Monday

Marcus Longley, health board chairman, said: "Unfortunately Allison Williams, our chief executive, is currently on an extended period of sickness absence. Therefore, there is a need to put in place interim arrangements."

He confirmed that Dr Hopkins, currently director of transformation at Cardiff and Vale health board has agreed to join them as the interim chief executive from next Monday.

She has 30 years experience in the NHS, including posts in public health and was responsible for setting up the south east Wales cardiac network.

"I am pleased that someone of Sharon's NHS experience at a very senior level will be joining us next week and I am confident that she will provide strong leadership as we address the many challenges that we now face," added Prof Longley.

Analysis by Owain Clarke, BBC Wales health correspondent

Ever since the scale of the failings of the care of mothers and babies became clear the pressure on Allison Williams has been mounting.

Eyebrows had already been raised that there were no resignations when the royal colleges' review of the problems was initially published at the end of April - one of the most damning ever assessments of failings in the NHS in Wales.

Ms Williams' careful and guarded responses in interviews that day, I'm told, left some families angry and frustrated.

Later some AMs on the assembly's health Committee told me that they had not been convinced by her evidence to them.

On Wednesday night, Ms Williams was due to appear before Rhondda Cynon Taf council, a body which has already lost confidence in her and her health board.

She won't now be appearing.

What is clear is that Cwm Taf Morgannwg health board faces huge challenges, not only in putting things right with families but in trying to rebuild its own reputation and public trust.

It's a baptism of fire for the new interim boss.