With the change, the children would be placed in protected custody with the US Department of Health and Human Services, in a "less restrictive environment", until they can be left with a relative in the US or by a state-funded guardian.
Prolonged detention of children is currently prohibited by court order in the United States.
The Department of Homeland Security of Donald Trump's administration is studying a proposal to separate children from their mothers who illegally cross the country's border with Mexico, according to the Reuters news agency.
With the change, the children would be placed in protected custody with the US Department of Health and Human Services, in a "less restrictive environment", until they can be left with a relative in the US or by a state-funded guardian.
Parents could be held in custody while they contest deportation or wait for asylum sessions.
The aim of the proposal is to inhibit mothers from migrating to the United States with their children. President Donald Trump has already called for a "catch and release" policy.
Currently, families with children in the process of being deported or applying for asylum are released quickly and can stay in the country until the case is resolved. Justice prevents the prolonged detention of children.
Between October 2016 and January 31 this year, 54,000 children and guardians were apprehended in the US, more than double the number seen in the same period in 2015 and 2016.
Source: Huff Post Brazil