Myanmar security forces were accused of a systematic campaign of sex crimes against Rohingya Muslims as hundreds of thousands fled the country last year.
Almost nine months after the exodus, Medecins Sans Frontieres (MSF) said it had witnessed an increase in the number of pregnant Rohingya women in Bangladesh refugee camps.
Women had been arriving at hospitals bleeding, suggesting they had tried to abort their pregnancies at home, the charity warned.
The organisation could not say how many of the pregnancies were a result of sexual attacks, but said more women were seeking help after being victims of sexual violence.
Georgina Brown, a doctor working with MSF, said: “Having a baby born from rape, especially one that they think has come from Myanmar – the community will not accept this baby.
“We do see cases where they obviously try to end the pregnancy themselves, which has often ended in death for the girl because she hasn’t sought healthcare.”
An average of 3,100 births a month are expected in Rohingya refugee camps over the next few months, MSF said.
The charity has treated 311 survivors of sexual violence among the Rohingya population between 25 August and 31 March, aged from nine to 50 years old.
Two thirds of women who had experienced sexual violence in Myanmar had not reported it to authorities or aid groups in Bangladesh, according to Human Rights Watch.
The UN’s special envoy on sexual violence, Pramila Patten, warned sexual violence had been “commanded, orchestrated and perpetrated” by Myanmar’s armed forces.
“Rape is an act and a weapon of genocide,” she said.
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Britain’s UN ambassador Karen Pierce has said Myanmar must hold a “proper investigation” into alleged atrocities against the Muslim Rohingya.
Some 700,000 members of the Muslim minority have been driven out of Rakhine state.