Police Scotland said the child died in hospital on Friday.
A five-month-old baby's death is being treated as "unexplained" by Police Scotland after officers sealed off a house in Livingston on Friday.
Police Scotland said the baby died in St John's Hospital on Friday, and eyewitnesses have said a house in Scott Brae has been sealed off by police since Friday.
A spokesman for Police Scotland said: "Police in West Lothian are investigating after a five-month-old baby from the Ladywell area passed away in St John's Hospital on Friday 15 November.
"The death is being treated as unexplained pending further enquiries and a report will be sent to the Procurator Fiscal."