THE “MEXICO CITY POLICY,” labeled by critics as the “global gag rule,” will now also be known — the State Department announced Monday — as “Protecting Life in Global Health Assistance.” That is an incongruous name for a policy likely to result in at least tens of thousands more deaths.

Under previous Republican presidents, the Mexico City policy, which withholds U.S. funding from foreign organizations that provide or promote abortion, applied only to the approximately $600 million the United States furnishes annually in family-planning funding. President Trump’s version affects almost all global health assistance — a full $8.8 billion. About $6 billion of that comes from the President’s Emergency Plan for AIDS Relief (PEPFAR), which President George W. Bush made exempt.

The consequences will be catastrophic. Developing countries have spent the past decade revamping their health systems so patients can get many types of care in one place. That means organizations will have to choose between abandoning clients in need of abortions and losing the funding they need to fight tuberculosis, malaria and more. PEPFAR’s inclusion will deal a heavy blow to HIV-prevention efforts, and may turn back one of the program’s greatest successes: a decrease in mother-to-child transmission. Worse still, judging from past experience, the policy may not even achieve its aim. Studies show that when the rule was last in place, under Mr. Bush, in many countries it resulted in more unintended pregnancies and abortions, not fewer.

The few exceptions to the policy, such as for humanitarian assistance and relief, are a thin silver lining in the cloud the United States has cast over the globe. The same goes for the State Department’s promise that the amount of global health assistance the United States provides will not change — only who receives it. Those dollars simply will not go as far if, for example, State hands them out to U.S.-based global health organizations, which are not covered under the policy, instead of their indigenous partners, which could use the funds not only to address present crises but also to equip their communities to manage future ones.

Sen. Jeanne Shaheen (D-N.H.) introduced legislation in January that would permanently repeal the Mexico City policy. The bill, which has only two Republican co-sponsors (both women) among a slew of Democratic supporters, seems unlikely to gain traction. But perhaps it could spark other action in Congress to counter the damage Mr. Trump’s policy is sure to do. For years, the United States has led the way in building a healthier world. It is up to lawmakers to stop the president from reversing that progress.