The two teenagers who fled a Sydney hospital with their three-day-old baby girl have been found.

The teen parents Jayden Lavender, 14, and Jenifer Morrison, 15, and their newborn baby were found at Willmot about 4.15pm on Thursday.

"Police are currently speaking to the teenagers and ambulance officers are assessing the infant as a precaution," a police statement said.

Officers believe the couple took their baby unnoticed by staff around 12.30am and left on foot.

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Police held a press conference earlier on Thursday to ask for help in finding the missing teens and have concerns for their wellbeing, particularly of the young mum and baby.

Detective Inspector Grant Healey said they had no information about where the young parents were staying but said they were not in trouble and "need all the help they can get".

Det Insp Healy said the couple smuggled the baby out beneath a blanket. CCTV footage from the hospital showed them leaving with an adult male.

Pictures of the young couple displayed on their Facebook pages show two young people very much in love.

Photographs on Jayden's page show the couple kissing and embracing.

On the couple's shared Facebook page entitled Jayden Jenny Lavender, photographs of the pair are captioned "me and my baby girl" and "I love u baby girl".

In one collage of three photos of the young couple is written "I"m so happy to be engaged to u baby" with hearts replacing the "o" in three of the words.

The cover photo on their shared Facebook page is one of the couple in each other's arms with the Snapchat puppy dog filter.

The photograph was posted on March 22, when Jenifer would have been in the final stages of her pregnancy.