The 11-year-old, who already suffers from a variety of health conditions, has also been diagnosed with Oppositional Defiant Disorder and is on the autistic spectrum.
Katie's son needs constant care and daily medication, without which he would not survive. Katie's mum, Amy, gave up her job to help Katie care for Harvey. Amy has to follow a strict routine in order to avoid Harvey's violent temper tantrums attributed to his behavioural conditions.
Katie has 'lost count of the number of televisions' that Harvey has broken during his tantrums and the model has admitted that she worries Harvey might hurt herself or his brothers and sister. Luckily, the former page 3 girl can anticipate when he will turn.
The star said 'I wish all those people who show ignorance about the disabled condition could spend a day with Harvey and see the reality of looking after a child like him.'
Katie has been open about her difficulties in encouraging Harvey's biological father, Dwight Yorke, to play a role in Harvey's life. She has expressed in the past her concerns about leaving him with Dwight as she fears he would not know how to handle his numerous conditions.
Katie says 'He's missing out on a very special little boy. Dwight should try. He would get so much love in return.'
Last week it was reported that Katie feels she can now trust her new husband, Kieran, to care for Harvey in her absence.
The model stresses that all she wants is for Harvey to have the best start in life.