Tania Clarence, 42, is to appear in custody at Wimbledon Magistrates' Court in south west London tomorrow, Scotland Yard said.
Post-mortem examinations are being carried out at Great Ormond Street Hospital on the children who have been named as three-year-old twins Ben and Max, and four-year-old Olivia.
They were found dead at their home in New Malden, south west London, on Tuesday night.
It is reported that the children were suffering from Spinal Muscular Atrophy (SMA) - a life-limiting genetic illness.
Their father, Gary, who works as a director at City bank Investec, was said to be away in the family's native South Africa with the couple's eight-year-old daughter when the deaths occurred.
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