“Left behind” children Luo Hongni, 11 (L) and brother Luo Gan,10, carry flowers to be used as feed while doing chores in the fields on December 18, 2016 in Anshun, China. Like millions of Chinese children, the four Luo siblings are being raised by their grandparents in rural China as their parents left to find work in urban areas. (Photo by Kevin Frayer/Getty Images)

Alkar Vito runs during the Children's Alka competition in Vuckovici village, Croatia, August 23, 2015. Children's Alka is a tournament which has been held every August in the Croatian village of Vuckovici since 1955, commemorating the victory over the Ottoman Turkish administration. The tournament is named after the ring, Alka, which children have to hit with their spears. (Photo by Antonio Bronic/Reuters)

Child models present creations at Dong Wenmei T100 Children's Collection during China Fashion Week in Beijing October 29, 2014. (Photo by Kim Kyung-Hoon/Reuters)

An adult helps a young girl light a cigarette as a band plays in the background in the village of Vale de Salgueiro, northern Portugal, during the local Kings' Feast Friday, January 5, 2018. The village's Epiphany celebrations, called Kings' Feast, feature a tradition that each year causes an outcry among outsiders: parents encourage their children, some as young as 5, to smoke cigarettes. (Photo by Armando Franca/AP Photo)

A fish jumps over a net as a boy works in a fish farm at Htantapin township, outside Yangon, Myanmar February 18, 2016. One in five children in Myanmar aged 10-17 go to work instead of school, according to figures from a census report on employment published last month, and the opening up of the economy since 2011 has triggered a spike in demand for labour. Many children work in fish farming and processing. At Yangon's San Pya fish market, the country's largest, girls and boys as young as nine clean and process fish and unload boats and trucks during 12-hour overnight shifts. (Photo by Soe Zeya Tun/Reuters)

In this Tuesday, July 29, 2014, photo, Syrian refugee Samah, 5, poses for a picture at Zaatari refugee camp, near the Syrian border, in Mafraq, Jordan. More than 2.8 million Syrian children inside and outside the country – nearly half the school-aged population – cannot get an education because of the devastation from the civil war, according to the U.N. children's agency, UNICEF. That number is likely higher, as UNICEF can't count the children whose parents didn't register with the United Nations refugee agency. (Photo by Muhammed Muheisen/AP Photo)

Children play with weapons during Children's Day celebration at a military facility in Bangkok, Thailand January 14, 2017. (Photo by Jorge Silva/Reuters)

A reveller parades on stage at the annual Trinidad and Tobago Red Cross Society's Children's Carnival Competition at the Queen's Park Savannah in Port-Of-Spain February 7, 2015. (Photo by Andrea De Silva/Reuters)