Cameron pressed on impact of benefit reforms on rape victims
David Cameron has vowed to "look carefully" at cuts to child tax credits to ensure women who become pregnant as a result of rape are not "penalised".
Tax credit payments for low paid workers will be limited to the first two children for new claimants under changes announced in the Budget.
Officials have been asked to "develop protections" for those who may have a third child as a result of being raped.
The SNP's Angus Robertson raised the issue at prime minister's questions.
Mr Robertson said rape was one of the most under-reported serious crimes, with 85% of victims not coming forward.
He said there were concerns that women might have to prove that their pregnancy was a result of rape.
Quoting the Women Against Rape pressure group, he said: "Asking women to disclose very difficult information and expecting them to be able to prove it in what is frankly a very hostile environment, when the DWP is trying to take your money away, will have appalling consequences."
Mr Cameron said he would "look very carefully" at the issue to make sure the government gets it right, saying it was not their intention to "penalise people who have been treated in this way".
But he said the principle behind the change in tax credits had been backed by acting Labour leader Harriet Harman, who he quoted as saying: "When I was going round the country talking specifically to women, so often they would say 'we've got one child, we'd really love to have another but we just can't afford it'."
Defending the plans to restrict child tax credits to the first two children, Mr Cameron said these families "are working hard and they feel it is unfair when other people can have families they would love to have... we've got to listen to that".
"But of course in cases like those he raises (where the third child is a result of being raped) we will have to look very carefully to make sure we look after them."
He said the government was also "investing in women's refuges and rape crisis centres to make sure we look after people who have suffered this appalling crime".