Jenifer Morrison, 15, and her boyfriend, Jayden Lavender, 14, who is the baby’s father, took their baby Aria Jayde Tanya from Nepean Hospital about 12.30am.

Penrith Detective Chief Inspector Grant Healy said the couple smuggled the baby out beneath a blanket and grainy CCTV footage from the hospital showed them leaving with an adult male.

“We don’t know what was operating on their mind at the time but we would love to be able to speak to those parents,” Insp Healy said.

“We’ve spoke to their parents and they’re giving us some information that we’re working on.

“We don’t known much about the adult at all ... We don’t know it it’s a family member but if the person who helped them leave is about we urge him to contact Penrith Police.

“Our primary concern is about the welfare of this young baby.”

The couple and baby had been in a ward in the maternity unit when they disappeared with the child and police still do not know whether they got in a car outside the hospital.

In a Facebook post Tracy Lavender welcomed the teenagers’ new arrival.

“This is Jayden 1 hour and my Most beautiful Girl in the world Aria Jayde Tanya Lavender born 10/04/2017 she is daddy’s girl 100% love you all Jayden Jenny Lavender and Aria,” she wrote online.

Nepean Hospital General Manager Brett Williams confirmed the baby was taken from the hospital early this morning without being discharged.

“We immediately notified the NSW Police Force,” Mr Williams said.

“We are concerned for the wellbeing of the mother and her baby and urge her to come forward.”

Jayden Lavender is described as being of caucasian appearance with brown eyes and short brown hair. He is believed to be wearing black and white hooded jumper.

Jenifer Morrison is described as being of caucasian appearance with long brown hair. She was last seen wearing a white hooded jumper, grey tracksuit pants and Ugg boots.

The man believed to have left with them was wearing a black Everlast jumper. Police said his identity is unknown.

Police said there were concerns for the welfare of all three children.

Police are asking the public to be on alert and report any sightings of the teenagers and baby. They have links to the state’s Central Coast and Mount Druitt areas.

The young couple has a joint Facebook page where they profess their love for each other and she has taken his surname.

Their families knew about the pregnancy.

Police are urging the public to phone triple-0 to provide any information about this abduction.