Pregnant women may be barred from entering the United States as President Donald Trump’s administration weighs a fresh immigration measure linked to birthright citizenship.

The proposed move is being considered after the US Supreme Court on Monday turned down Trump’s bid to end birthright citizenship, the constitutional principle that gives automatic citizenship to children born on American soil.

If implemented, the measure would represent another push by the Trump administration to curb what it describes as “birth tourism”, where foreign nationals travel to the US during pregnancy so their children can obtain American citizenship at birth. Although the practice exists, experts have said it accounts for only a small number of births.

The administration had maintained that birthright citizenship fuels illegal immigration and “rewards illegal aliens who not only violate the immigration laws but also jump in front of those who follow the rules”.

Stephen Miller, a senior adviser to Trump, said the White House would take “a hard look” at preventing pregnant foreign women from travelling to the US.

The White House deputy chief of staff for policy and homeland security said: “You have to now think very carefully about who you let into your country, even on a temporary basis because of the possibility for birth tourism.

“That people come here just to have babies on American soil, and that baby gets to be a citizen for life.

“If a person comes here nine months pregnant to go and look around at some things, in a couple of weeks that is the mother of a lifetime American citizen and a direct line into American cash and welfare for the rest of that child’s life.

“There are a lot of things we need to have a hard look at.”

Miller made the remarks after the Supreme Court blocked Trump’s Day One executive order which sought to deny US citizenship to children born to parents living in the country illegally or temporarily.

In a 6-3 ruling, the court held that stripping babies born in the US of automatic citizenship would breach the 14th Amendment and was therefore unconstitutional.

The case marked the first significant legal challenge to the 14th Amendment in more than 100 years, as Trump attempted to use executive authority to redefine who qualifies as an American citizen. (Tribune News)