Lucy Letby helped to create a banner to celebrate a premature baby reaching 100 days old – then tried to kill her, a court has heard.

The little girl had reached the milestone after she was born “very, very prematurely”, weighing only 535 grams.

Doctors at Wirral’s Arrowe Park Hospital gave the girl a 5% chance of survival, but she stabilised and months later was well enough to be transferred to the Countess of Chester Hospital, where nurse Ms Letby worked.

Weeks later, on the evening of 6 September 2015, nursing staff on the neonatal unit, including Ms Letby, put up a party banner in celebration of the baby’s 100th day of life.

The infant’s parents joined in the celebrations as a cake was brought into the unit, Manchester Crown Court heard.

They later went home, but received a call in the early hours of the next morning to say their daughter had vomited.

Medics noted the baby, referred to as Child G, had projectile vomited at about 2am and her abdomen appeared “purple and distended”.

Her oxygen levels dropped, and she stopped breathing several times over the next few hours before she responded to breathing support on ventilation.

The prosecution alleges Ms Letby overfed Child G with milk through a nasogastric tube or injected air into the same tube.

The next day, the court heard, she messaged an on-duty colleague asking how the baby was, saying “poor parents”, then adding: “Awful isn’t it. We’d all been sat at desk at start of the shift making banner.”

The defendant later told her colleague: “Needs to go out.”

The colleague replied: “Too sick to move.”

Ms Letby said: “Oh no. Any idea what’s caused it?” To which, came the reply: “Nope. Just seems to be a circ (circulatory) collapse, chest seems clear.”

‘She looks awful’

The court heard Ms Letby visited the unit briefly again later that evening.

Afterwards, she messaged her colleague – who had finished her shift – saying: “She looks awful, doesn’t she.”

On learning the baby was to be transferred to another hospital, Ms Letby responded: “Just hope they get her there.”

Child G was transferred at 3am on 8 September back to Arrowe Park, where she recovered, but was moved back to the Countess of Chester more than a week later, the court heard.

The Crown alleges Ms Letby made two more attempts to murder Child G on 21 September.

Jurors were told Child G now has quadriplegic cerebral palsy and requires round-the-clock care.

Ms Letby, originally from Hereford, denies murdering seven babies and the attempted murders of 10 others between June 2015 and June 2016.

She had been given specialist training in care for the sickest babies at the neonatal unit in the Countess of Chester Hospital.

The trial continues.