They said that frequent and erratic interruptions to baby care could affect brain development.

London - A psychotic mother smothered her baby after her marriage hit a crisis and she began using cannabis heavily.

Carly Jacques developed post-natal depression three months after giving birth, when her husband confessed he had made one of her best friends pregnant during an 18-month affair.

Jacques started taking cannabis – at one point using £60 (about R800) worth of the drug every day or two – and developed mental problems.

By the time she smothered daughter Skye, when the infant was seven months old, she was suffering from delusions and had become convinced neighbours were out to harm her and the child.

On Friday the 32-year-old customer services manager was made the subject of a hospital order after a judge ruled she needed to be given treatment rather than punishment.

Jacques had previously admitted the rarely-used charge of infanticide – defined as the killing of a child under the age of 12 months by their mother, but who at the time of the act was of disturbed mind, having not fully recovered from the effect of giving birth.

Following the case, her mother, Julie Tame, said: “Carly was a fantastic mum. Her husband cheated on her with one of her best friends and that triggered her mental decline. He destroyed her world.”

The couple had been married five years but had been together since Jacques was 18. Leicester Crown Court heard that following her husband Mark’s confession in March last year, Jacques began showing symptoms of post-natal depression and turned to cannabis.

She started to suffer delusions, suggesting there was a body in her attic and she was being filmed in her home.

Her GP prescribed Prozac and referred her to a counsellor.

The court heard that the night before Skye died in October, Jacques had been smoking cannabis and drinking alcohol at a party. When her husband woke up at their home in Leicester the following morning, he went downstairs to discover Jacques clutching the “obviously blue” body of their daughter.

She was holding a blade in her hand and said: “What have I done?” She then slashed her own wrists as her husband – who was not in court – struggled to disarm her.

Jacques then slashed her neck with a carving knife before she was again disarmed and taken to hospital.

Skye suffered no visible injuries and the cause of death was given as smothering.

Jacques needed 40 stitches for her injuries. Police arrested her in hospital on suspicion of murder and she admitted what she had done. She told police: “I just thought we could go to sleep and we would both be safe.”

The court heard Jacques had tried to commit suicide the week before she smothered her child.

Mary Prior, defending, said Jacques was “a good mother” but it was clear that what caused the tragedy “was the admission from her husband of an affair”.

Sentencing her, Judge Michael Pert QC said: “I am satisfied that what led you to that terrible act was illness rather than wickedness.”

Jacques was made the subject of a Section 37 Hospital Order. She was also handed a Section 41 Restriction Order.

This means doctors must first seek permission from the Ministry of Justice before Jacques can be discharged from hospital care. - Daily Mail