She was sentenced in 2003.

An Australian mother who was convicted of killing her four children has lost her appeal. Kathleen Folbigg was found guilty of killing her four children by smothering in Sydney over a 10 year period in 2003. She was convicted on three counts of murder and one count of manslaughter and sentenced to 25 years in prison. Folbigg, who has continuously denied any wrongdoing, filed an appeal against claims that her children did not die of natural causes. The appeal, which included a petition signed by 91 scientists, doctors, and other relevant professionals, has been denied. 53-year-old Folbigg was convicted over the manslaughter of her first child, Caleb, and the murder of her three others, Sarah, Patrick and Laura in 2003.

Each child, aged between 19 days and 18 months, all died suddenly in their home over the course of 10 years. Postmortem examinations could not determine the causes of death for all four children.

According to ABC, an inquiry was ordered into Folbigg's conviction after her legal team argued that the children could have died of natural causes, as two of the babies had a genetic mutation that could have led to Sudden Infant Death Syndrome (SIDS). An autopsy showed that one of the babies had an inflamed heart muscle that could have led to death. Another suffered from epilepsy and is likely to have died following a seizure. The remaining two children were recording as dying by SIDS. In 2019 a judge found that all four children could not have died of natural causes. Folbigg later appealed this decision and lost her case this week. According to the Court of Appeals, "this was not a case in which the judicial officer's conclusion was at odds with the scientific evidence".

The court added that there was only a "theoretical possibility" that the babies had a genetic defect that could have led to SIDS.