Many are held as sex-slaves and if they escape are rejected by their families.
Joséphine, from Masisi in the eastern Democratic Republic of Congo, DRC, says that she chose to join the National Congress for the Defence of the People, CNDP, militia in order to escape a marriage that was being forced upon her by her parents.
"I joined the CNDP to avoid revenge from [the man that was to be] my husband," Joséphine said. Her parents had wanted her to marry a widowed man when she was just 16.
"[I felt that] joining the CNDP… would give me protection," she said.
In 2009, Joséphine left the militia. While a member, she had had a child but didn’t know who the father was. She said that she had been raped by several CNDP battalion commanders.
After leaving, she stayed with a Centre for Transit and Orientation, CTO, which assists ex-combatants, in Masisi, eastern DRC, before deciding to return to her home village.
"I had no other choice but to marry a policeman,” she said, knowing that she did not want to return to her former life in the militia. The man that she married agreed to accept her son.
Girl soldiers, who are often forced to marry militia commanders, tend to have difficulties leaving and reintegrating into civilian life.
In 2004, the United Nations children’s agency UNICEF launched a national programme to help former child soldiers adjust to their new circumstances. But since it started, only two per cent of those it has assisted have been women.
Juvénal Munubo, head of a child soldiers reintegration programme for the NGO Caritas in Goma, eastern DRC, argues that this is disproportionally low, compared to the number of women that are estimated to be members armed units.
He says research suggests that out of the 250,000 child soldiers now mobilised worldwide, between 30-40 per cent - depending on the region – are young girls.
Munubo says that there are a couple of reasons that girls end up joining the ranks of militias.
"Often, those aged 10 to 14 are simply abducted by soldiers or militia men on the way to school, in the fields or when they go to fetch water," Munubo said. “[Another reason] is that girls believe that by becoming soldiers they can also protect themselves from abuses committed by men."
This was certainly the case with Joséphine.
"My husband threatened to retaliate. [I felt that] joining the CNDP…would give me protection," she said.
But when the likes of Joséphine join armed groups, the life they have is not what they expected.
"The [fate] of girl soldiers… is to be used as sex slaves," Emmanuel Gahima, in charge of the CTO in Nyanzale, 120 km north of Goma, said.
"Girls are reluctant [to leave the armed group] since they are haunted by fear and insecurity,” Munubo said, adding that, as was the case with Joséphine, families often reject children that have served with militia units, regarding them as troublemakers.
Humanitarian activists say that the low number of girls coming into CTOs points to the fact that they find it harder than boys to leave the armed groups.
Béa Lumoo, 16, one of three girls admitted to the CTO at Kanyabayonga, 155 km north of Goma, suffered a terrifying ordeal when she tried to flee.
"One day, my battalion commander took me to his bivouac (a military encampment) to rape me,” Béa said. “Then he said that if I rebelled or tried to flee, he would kill me."
She did eventually manage to escape, but when she turned up at the CTO she had terrible scars all over her back.
Experts also say that former girl soldiers are hesitant to return to their families and communities because they are ashamed of what they have gone through.
"Each girl enrolled as a combatant is persona non grata in her former community," said Gahima, from the CTO in Nyanzale. She is often considered a prostitute, due to the role she was forced to perform in the forest, he explained.
Many demobilised girls leave with young children whom they cannot afford to feed, and rejection by the community makes their life all the harder.
Some of these girls resort to prostitution to survive. Others drift back into the armed groups that they tried so hard to leave. Some end up dying from sexually-transmitted diseases, which they have contracted while in rebel ranks.
Matilde Ngutuye, in charge of the CTO at Mweso, 100 km northwest of Goma, says that humanitarian organisations have launched awareness campaigns to inform parents of children’s rights.
But such campaigns have had only a limited effect, and only a few girls - usually those that are sent to the front-lines rather than used as sex slaves – are taken back.
"My father didn’t want to see me again since he had heard people saying how soldiers had abused me," Joséphine said.
This was also the case with Mireille, 16. After she left the Nyanzale CTO, she tried to return home to her family, but they didn’t want anything more to do with her, given what she had been through.
She therefore moved in with another former child soldier from the CTO, who was just 17. But they only lived together for three weeks before she decided to move out. Having nowhere else to go, Mirelle became a prostitute.
Taylor Toeka Kakala is an IWPR-trained reporter.