SEN. JESSE HELMS and his supporters are continuing their fight to dismantle U.S. aid for birth-control programs in developing countries. Sen. Helms has already attached a crippling amendment to the foreign aid bill now being considered on the Senate floor and may attempt to add even more destructive language to the measure.

Ostensibly, the Helms amendment is intended only to prevent U.S. money from being used for coerced abortion and infanticide in China -- alarming reports of such practices have been widely circulated -- and this is an objective with which no one would quarrel. But the fact is that, under current law, no U.S. money now supports such activities either directly or indirectly. The Helms amendment is thus unneeded for its stated objective -- and dangerous for its far-reaching consequences.

The amendment would prevent any U.S. money from being used, either directly or indirectly, in any country that "permits, officially or in practice, infanticide or coerced abortion," or by any organization that gives any kind of direct or indirect aid to such country. Sen. Helms states in a draft report that the language is deliberately "very broad" so that aid may be cut off not only to China but also to any other country where the forbidden practices might be suspected, even if they were without official sanction.

Since infanticide is a tragic occurrence in nearly every country of the world, including this one, a rigorous application of the amendment obviously could serve to terminate all birth control aid. The most direct casualty of this amendment would be U.S. assistance to the useful and well-accepted U.N. birth-control programs. The United Nations includes China among its aid recipients. However, contrary to recently published allegations, U.N. money is narrwly confined to stated purposes and no U.N. money has ever been used for abortion, whether voluntary or coerced, much less for infanticide.

Senators who are rightly concerned that U.S. money not be misused don't have to rely on birth- control advocacy groups for this assurance. The Reagan administration's own Agency for International Development has repeatedly investigated U.N. programs and reaffirmed that they conform to longstanding U.S. policy against aiding even voluntary abortions. The most recent report, issued only two months ago, once again gave the United Nations a clean bill of health. Of course, the United States should use all its moral suasion to press for stronger action by the Chinese government against coercive practices. But senators should remember that voluntary family-planning programs are the best-proven and most humane way to reduce resort to the age-old practices of abortion and infanticide.