Julia Quenzler
An infant health expert has told jurors it is "exceedingly unlikely" that Constance Marten and Mark Gordon's baby died of hypothermia.
Professor Peter Fleming was called by the defence to give evidence at the couple's trial for the gross negligence manslaughter of their newborn Victoria.
Her body was found in a bag at an allotment in Brighton last March after a weeks-long search for the family.
The couple deny manslaughter and a number of other charges.
Prof Fleming - professor of infant health and developmental physiology at the University of Bristol - told the Old Bailey: "I have seen no evidence of hypothermia as a cause of death.
"The description of how she was being cared for would make hypothermia exceedingly unlikely."
Prof Fleming later agreed that the account of how the baby was being cared for had been given to him by Ms Marten.
The expert witness said he had studied babies in Mongolia who safely slept in their mother's clothing when the "room temperature was commonly zero or below zero".
Judge Mark Lucraft asked: "Presumably they were wearing traditional Mongolian clothing?" Prof Fleming replied: "Correct."
Ms Marten has previously told jurors Victoria died on 9 January, but prosecutors allege she died weeks later.
Prof Fleming said a measurement of Victoria's foot length suggested she was not born prematurely and was about two to three weeks old when she died.
He added he could not confirm Victoria was eight weeks old when she died.
Prof Fleming said: "All the pointers suggest to me that she was much younger. The best fit is that she was two or three weeks."
Ms Marten's account of the death is that she fell asleep sitting up in a tent and "keeled over", waking up to find Victoria dead.
Prof Fleming said he had seen two cases in his career in which a breastfeeding mother had been sitting up, and fell asleep over the baby who died.
Prosecutor Tom Little KC asked the witness what his response would have been had Ms Marten told him she was going to be sleeping in a tent in temperatures between 4 and 10 degrees, with only "a baby grow and a vest".
Prof Fleming replied: "I would say it would be inadvisable, but if you have to then keep your baby inside your coat."
Asked by the prosecutor what he thought of the £40 Argos tent the couple purchased to stay in, Prof Fleming said it would not be "ideal" accommodation.
The jury has heard that the couple kept Victoria's body in a shopping bag for days or even weeks after her death.
The judge asked Prof Fleming a question posed by the jury about what the optimum time after death to carry out a post-mortem examination would be.
"The sooner the better," Prof Fleming said. "Within 24 hours ideally."
Both defendants deny manslaughter by gross negligence, perverting the course of justice, concealing the birth of a child, child cruelty, and causing or allowing the death of a child.
The trial continues.
