The Bayswater Support Group, representing around 800 parents of children with psychogenic transgender identification, including former patient Keira Bell, sent a letter of pre-action to the MHRA and HRA. They are demanding a halt to the Pathways clinical trial or face a judicial review. The MHRA licensed the study and the HRA oversees ethical requirements. The study came about after a review by pediatrician Hilary Cass found extremely limited data on the harms and benefits of puberty blockers — gonadotropin-releasing hormone analogs — in children. Cass recommended further research in children in early and middle puberty before moving on to other treatments. Campaigners against puberty blockers in gender-questioning children have taken the first steps to legal action to stop the study.