Shraavya and Sumukh, two Indian-born engineers who work in California, are thrilled to be expecting their first child.

They know they are having a boy and that he is due on Feb. 19.

What they are far less certain of is whether their firstborn will be a U.S. citizen, after President Trump issued an executive order that seeks to end the Constitution’s guarantee of birthright citizenship.

The order has injected a dose of anxiety and uncertainty into an otherwise exciting, joyful time for the couple who are in the country legally with long-term work visas.

“You already have a lot of things to be stressed about,” said Shraavya, 31, the mother to be. “Then this came into the picture.”

The birthright citizenship order, issued in Mr. Trump’s first hours back in the White House, has prompted a wave of legal challenges and a succession of sharp critiques from the federal courts. Judges in Maryland and Washington have issued nationwide injunctions halting any action to carry out the directive, and another in New Hampshire took similar action on Monday.

Legal experts emphasize that birthright citizenship cannot be revoked through an executive order, like the one issued by Mr. Trump on Inauguration Day. Ending birthright citizenship would require an amendment to the Constitution, which must be approved by two-thirds of both chambers of Congress and subsequently ratified by the legislatures of three-fourths of the states. Mr. Trump has not pursued such a change to the Constitution, but his order and the intense legal blowback is nonetheless sowing confusion and stress among many immigrant families.