China has vowed to reunite families and return dropouts to school after publishing its first comprehensive study on left-behind children.

Following a door-to-door survey that began in March, the Ministry of Civil Affairs has said that 9.02 million children age 16 or under have been left in the countryside by migrant worker parents.

The research found that more than 90 percent of them are growing up without either parent and are in the care of grandparents, friends or relatives. An additional 360,000 have no guardian.