Tania Clarence has admitted killing her three disabled children at their New Malden home.
Appearing at the Old Bailey, Clarence pleaded guilty to the manslaughter of four-year-old Olivia, and three-year-old twins Ben and Max by diminished responsibility.
They all suffered from Spinal Muscular Atrophy, a genetic disorder which leaves children with little control of their movements and can drastically shorten life expectancy.
The 42-year-old, who denied their murder on April, has been remanded to a secure psychiatric unit where she will be examined prior to a trial, which has been given a provisional start date of 23 February.
Police were called to the family home after friends said they had been unable to contact the family for 24 hours.
Husband Gary was reportedly away in South Africa with the couple's eight-year-old daughter when the deaths happened.
South African-born Clarence was taken to hospital with minor injuries but was later discharged and arrested.