Constance Marten and Mark Gordon will appear in court on Friday after the remains of a baby were found in woodland earlier this week.
Marten, 35, and Gordon, 48, went missing eight weeks ago with their newborn and were the subject of a large-scale police hunt.
They are due to appear at Crawley magistrates court charged with gross negligence manslaughter, concealing the birth of a child and perverting the course of justice.
The couple were arrested in Brighton on Monday after a member of the public tipped off the police that they had spotted them.
The couple did not reveal the location of the baby but police found remains in an area of Sussex woodland on Wednesday. Detectives believe the infant had been “dead for several weeks” and said it was not possible to tell if it was a girl or a boy.
Marten and Gordon had been missing since 5 January when their car was found abandoned and on fire next to a motorway in Bolton.
Marten, who was born into an aristocratic family with links to royalty, met Gordon in 2016 when she was a drama student.
Speaking at a press conference on Thursday, Det Supt Lewis Basford, of the Metropolitan police, confirmed that the case had been referred to the police watchdog, the Independent Office for Police Conduct (IOPC) because the death occurred during a missing person’s investigation.
Basford said: “While there are still many unanswered questions, it is important that we give the investigation team the time and space they need to establish more details about the circumstances of this tragic death.
“At this stage, we have not yet been able to confirm the baby’s gender and a postmortem examination has not yet taken place.
“Despite this, based on the inquiries we’ve carried out so far, we believe, sadly, the baby had been dead for several weeks before they were found. It’s too early for us to provide a more specific date.
Also speaking on Thursday, Ch Supt James Collis, from Sussex police, said: “We have seen an outpouring of public sorrow following yesterday’s heartbreaking discovery and have been overwhelmed by kind messages and support to those involved in this challenging search and investigation.”