'How many children don't we know about?' - Brianna Ghey's mother
Esther Ghey has told the BBC it is "really important" that social media companies work alongside Ofcom to keep younger people safe online.
Ms Ghey, mother of murdered teenager Brianna Ghey, was speaking to the BBC alongside other bereaved families whose children's deaths were linked to social media.
Her daughter Brianna was murdered by 15-year-olds Scarlett Jenkinson and Eddie Ratcliffe in 2023.
Jenkinson and Ratcliffe had watched videos of the torture and murder of real people on the dark web - internet sites which are only accessible via an encrypted browser - in the weeks before they killed Brianna.
"I wonder how many children are actually struggling with their mental health, how many of them have been affected by self-harm that we don't actually know about," Ms Ghey told the BBC.