A premature baby, described as "smaller than a kitten" at birth, has been discharged from a Chinese hospital after 111 days of intensive treatment.

The boy weighed just 900 grams when he was born 15 weeks earlier than normal.

His blood vessels were "as thin as a thread", a staff with the No 2 People's Hospital of Shenzhen, in south China's Guangdong province, said after the baby left for home.

His life was threatened by suffocation, anaemia, electrolyte disturbance and apnoea syndromes and his weight fell to 750 grams.

Normally babies weigh 2,500 grams after 40 weeks of pregnancy.

It is very rare to save such a small and weak baby, doctor Li Qi said.