Police are investigating what happened to a boy pronounced dead 12 hours after his birth in a Tsuen Wan flat. The mother, 34, gave birth in the bathroom of her second-floor flat in Discovery Park, Castle Peak, at midday on Thursday. She and the baby were in bed when her husband, a businessman, 42, returned home at 7pm. The husband told police the baby was dead when he returned home. His wife refused to hand the child over and would not let him call for help. He eventually called the police at 1am yesterday. The baby was sent to Princess Margaret Hospital, where he was pronounced dead. The woman was also admitted but was unable to give a statement to police officers because of her emotional state. Results of a postmortem examination gave no clues as to the cause of the boy's death. 'Further tests could help us determine whether the baby died when he entered the world or there were other reasons,' a police spokesman said. The couple have four children, the eldest of whom is 12.