Yazidi refugees
Islamic State has been systematically attacking people from the Yazidi ethnic minority since August 2014 Reuters/Rodi

Fighters from the Islamic State (Isis) are using forced birth control on the slaves they capture to avoid them getting pregnant and halting the cycle of sexual abuse. The girls, some as young as 16, describe being force-fed pills, sustained physical abuse leading to the death of unborn babies and unwanted injections.

Isis (Daesh) have implemented their own version of Shariah law on inhabitants living in large parts of Syria and northern Iraq, citing obscure Islamic texts stipulating a man must ensure that a woman he enslaves is free of children before having intercourse with her. Under IS law sexual slavery is legal and the transfer of slaves between fighters is common.

But IS believe that a slave must have undergone istibra' — "the process of ensuring that the womb is empty" and a pregnant slave will not be accepted by the receiving party. The extremists have even published a pamphlet suggesting that it is legal for a man to rape a woman that he has enslaved, but the injunction against raping a pregnant slave is the only way that a captive will avoid being repeatedly violated.

In an investigation by the New York Times some 36 women of the Yazidi sect, that have been systematically targeted by the extremists as heretics, revealed details of their lives once captured by brutal IS fighters.

The group's leaders believe that sexual slavery is allowed as it was practiced during the Prophet Muhammad's time – and one of the worst groups to suffer at the hands of these rules are the ethnic Yazidi religious minority. The jihadists often pas the girls between each other in exchange for cash or goods and to keep this sick trade going it is crucial that the women do not become pregnant.

One of the former captives said to the newspaper: "Every day, I had to swallow one in front of him. He gave me one box per month. When I ran out, he replaced it. When I was sold from one man to another, the box of pills came with me," said one of the girls, who learned only months later that she was being given birth control.

The Yazidi's homeland near Mount Sinjar was decimated in August 2014 and since then over 700 rape victims from the ethnic group have been treated at a UN-backed clinic in northern Iraq.

According to gynaecologists in the clinic just 5% became pregnant during their enslavement which is considerably low fertility rate for the victims of rape. Some of the former slaves that have escaped the clutches of the extremists were forced into having abortions.

In April 2015, it was estimated that two girls captured by IS kill themselves every day after being abused by the insurgents. An Iraq-based aid worker only known as Yousif told the Express that up to 60 girls commit suicide every month after a life of "shame", fearing that their families will not accept them back should the terrorists release them.

In January this year a UN report estimated that 3,500 people – mainly Yazidi women and young girls – were being kept as sex slaves by IS in Iraq.

"Those being held are predominantly women and children and come primarily from the Yazidi community, but a number are also from other ethnic and religious minority communities," the joint report issued by UN Assistance Mission for Iraq and UN human rights office said.