President Trump sent shock waves rippling through the assisted reproduction and immigrant communities recently when he said he intended to end birthright citizenship.

Birthright citizenship refers to the constitutional rights of anyone born on U.S. soil. Under the 14th Amendment to the U.S. Constitution, everyone “born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.”

President Trump and his administration are claiming that the clause in the middle of that sentence (“subject to the jurisdiction thereof”) means that the 14th Amendment was only intended to apply to the children born to legal residents of the U.S.

While the president is ostensibly considering this move because of what he perceives as a serious problem of immigrants here illegally and taking advantage of U.S. resources and protections, ending birthright citizenship could also affect the children of parents from other countries who use assisted reproduction and U.S.-based gestational carriers to grow their families. Today, even if both intended parents are non-citizens, their babies enjoy U.S. citizenship as long as they are born in the U.S. If the president successfully changed the birthright citizenship law that could leave such children’s citizenship in question.

In arguing for changing the law, President Trump erroneously claimed that the U.S. was the only nation in the world that granted birthright citizenship. In reality, Canada, Mexico, and at least 28 other countries also provide birthright citizenship to children born there.

Most constitutional scholars agree that a sitting president cannot use an executive order to change birthright citizenship. Instead, Congress would need to act to repeal the 14th Amendment. Any attempt by President Trump to actually issue and sign such an executive order would be met by legal challenges, but it could nevertheless create confusion, at least temporarily, for non-citizens whose children are born in the U.S.