Women migrants fleeing wars, political instability and poverty are taking contraceptives in the expectation of being raped but are so desperate they still embark on the journey, a human rights group said on Wednesday.

Women and girls who risk sexual violence as they flee their home countries are getting contraceptive injections as a precautionary measure, said researcher Hillary Margolis from New York-based Human Rights Watch.

"For someone to know that they are at such risk of sexual violence, and yet they are determined to continue on that journey," she told Trust Women, an annual women's rights and trafficking conference hosted by the Thomson Reuters Foundation.