If the article tells any sort of truth, then the midwife did realise parts of the placenta were retained - she is said to have told the husband it would come out naturally.
To be in the clear she would have to convince the inquest that she never said that.
Or alternatively show why she chose to leave the wife under those circumstances.
She would also have to show that the husband did not have to ring her several times after the event before she agreed to come out, as he claims.
Also, why she did not ring an ambulance straight away when she realised there was haemorrhaging.
My 12yo did better than this during a recent family crisis: he didn't stop to ask whether the patient would want an ambulance called- he realised it was his responsibility, so he did it.