Urgent search for missing Sydney newborn and teen parents

A three-day-old baby girl and her young parents have gone missing from a Syndey hospital, and police have serious concerns for their welfare.

CCTV footage captured the parents, who are 14 and 15, leaving Nepean Hospital with the baby about 12:30am on Thursday, the Syndey Morning Herald reports.

It's believed they were accompanied by an unknown man.

Detective Chief Inspector Grant Healy said police have serious concerns about the newborn and the mother, and says doctors need to see Arias, the baby, to monitor her wellbeing.

Det Insp Healy says "For Jenifer and Jayden, the two parents, you're not in trouble, we'd really appreciate if you could go to the hospital so we can check out and see if you're alright and just make sure everything is fine with you."

Jayden Lavender, 14, is described as being of Caucasian appearance, with brown eyes and short brown hair, last seen wearing a black and white hoodie.

Jenifer Morrison, 15, is described as being of Caucasian appearance with long brown hair, last seen wearing a white hoodie, grey tracksuit pants and Ugg boots.

It's believed that the man they left the hospital with was in a black Everlast jumper.