Baby Elsa, who was discovered by a dog walker in sub-zero temperatures, is now in foster care.
Police have released details of a woman they want to trace after the discovery of a baby in a shopping bag in Newham.
Baby Elsa, who was found by a dog walker in sub-zero temperatures, has since been discharged from hospital and is in foster care.
The Metropolitan Police said a woman was seen entering Greenway at around 20:45 GMT on 18 January.
Elsa was found 30 minutes later at the junction of Greenway and High Street South.
Ch Supt Simon Crick said the whole country had been concerned for Elsa and her mother’s welfare.
He said the woman officers wanted to trace was black and was wearing a large dark coat with a light-coloured scarf or hood around her neck and had a rucksack on her back.
“Since our first appeal we’ve had 17 reports from the public sharing information and I can assure people that every single one is assessed and progressed where that information is thought helpful,” he said.
“Baby Elsa is safe and well. I’m sure people will have seen recent reporting that she has now left hospital. Our colleagues in Newham Council continue to make sure she’s well looked after and cared for.
“My team are continuing their work. We’ve collected a considerable volume of CCTV footage. While we’re still examining it in detail, we have identified a woman we would like to speak to, and a witness who may have seen her.”
He added that officers believed the woman entered Greenway from High Street South and left heading in the direction Fabian Street.
The Met also wants to trace a witness officer think saw the woman in the vicinity.
Ch Supt Crick said: “He is believed to be male, wearing a dark-coloured hooded coat, with a backpack; the coat or backpack has a reflective strip on the rear of it. He exited the Greenway at around 21:10.”
Elsa was born approximately an hour before she was abandoned and still had her umbilical cord.
Doctors believe she was a full-term baby and weighed 6lbs 6oz (2.9kg) when she was found.
Since then, officers have carried out door-to-door inquiries, speaking to residents and businesses.
“We’ve also spoken to local hospitals, social workers and local charities. All of the information we have so far suggests it’s highly likely Baby Elsa was born after a concealed pregnancy and was not a service user of these agencies,” Ch Supt Crick added.
“I want to appeal directly again to Baby Elsa’s mother. Your daughter is safe and well, but we need make sure that you are too. You might need urgent medical care and support, and we can help you. Please call 999 and speak to us, or go to hospital.
“Lastly, I’d like to say that although comments online have been largely incredibly kind, supportive and understanding, there have been a small number of abusive and negative comments that are both unnecessary and unhelpful. All of us are looking at this from a position of privilege in that we have no idea what Baby Elsa’s mother is going through.
“Please consider what you post – and the possibility that she might even read it – and help us with our primary aim of identifying her to make sure that she’s OK.”