North Yorkshire Police today posted the appeal on video sharing site YouTube in a bid to trace the woman, who is thought to have been a pupil at a local school at the time of the discovery in 1999.
The baby was found wrapped in a black jumper and plastic bags at Burythorpe Bridge, on an unclassified road between Norton and Stamford Bridge, on the morning of April 30, 1999.
Police examinations suggested the baby boy died in January 1999 and was around 34 weeks old at the time he died. No signs of injury were found though the level of decomposition meant it was impossible to determine whether he was born alive or to establish a cause of death.
In January 2001 the coroner recorded an open verdict at the inquest and the baby was given a burial with a graveside service, despite no-one knowing who he was and how he died.
In the North Yorkshire Police video Detective Constable Sarah Bullock, named in the caption only as ‘Sarah’, says: “I am here on behalf of my team, to ask for your help, to find out what happened to a baby boy, in the Menethorpe area, near Malton, around Christmas 1998.
“This little boy was found on a short track. I know that he was cared for, because he was found wrapped in a black jumper, which may have belonged to his mum.
“He was found in early 1999. An appeal was held but his mum was never found. He would have been born in 1998, that is the same year the first Harry Potter book was published, and films such as Sliding Doors, Little Voice and Shakespeare in Love were in the cinema.
“I believe that his mum was probably young, and may have attended a local school at the time, and she will now be around 30 years old.
“I appeal to her friends and family, or anyone who may have lived in the area at the time, and knew somebody, and noticed a change in their behaviour, such as a difference in clothing, not attending PE at school, turning down invitations to Christmas and New Year’s parties, but later returning to her normal self, to contact me.
“I am also concerned about this little boy’s mum, and I want you to know if you are listening that I can get you all the help and support that you need. It’s never too late to do so, please contact me. Thank you.”
A message posted on the video said: “If you can help, or know anything which might be of use, no matter how small, please contact Sarah on 07581 297866.”
The mystery is one of a number of cold cases being reviewed by North Yorkshire Police.
As part of the original investigation, 600 vehicles were stopped on the Norton to Stamford Bridge road with officers speaking to every driver to try and shed some light on the baby’s death.
North Yorkshire Police say no witnesses were found and none of the motorists had any information that could help the police with their enquiries.
A statement about the case on the force’s website posted four years ago says: “Officers cast the net wider and national enquiries established possible identities for the baby but all leads were eliminated either by DNA comparison or other investigative methods.
“Eventually, all lines of enquiry to identify the baby boy and track down his parents were completed, however the investigation is continually reviewed and officers are still determined to uncover the truth.
“There are several theories that explain what could have led to the baby being abandoned at Burythorpe Bridge or why his mother was unable to come forward at the time.
“The police are aware that the mother would have needed medical assistance following her baby’s birth and, critically, further support when he died. Twelve years on that support is still available to her and will be equally important.
“Detectives working on the case would still like to hear from the baby boy’s parents or anyone who can help identify them. They will be handled in a compassionate and caring manner by specially trained officers, should they come forward.”