The choices of birth-control methods available to American women will increase next year when an intrauterine contraceptive device now available in other countries will be distributed in the United States.

The IUD, the Copper T380A, was developed and patented by the Population Council, an international, nonprofit research organization, and was approved by the Food and Drug Administration in 1984. Since then, Finishing Enterprises Inc., a small, privately held company in North Tonawanda, N.Y., has manufactured the IUD for distribution abroad, including Canada, mainly by pharmaceutical companies, the Agency for International Development and the International Planned Parenthood Federation.

A report in Monday's National Law Journal will say the council and "an unidentified company" will make the Copper T380A available in this country.

Finishing Enterprises and the council declined to name the company.

"The Population Council wants to ensure that accurate and balanced information about this important contraceptive is released to the media and the public at the same time," a council spokeswoman said in Manhattan.

"To be fair about this, we are holding a press conference on Oct. 28, at which time questions about all aspects of this subject will be answered," the spokeswoman said.

For nearly three years, the only IUD sold in the United States has been Alza Corp.'s Progestasert, which, to enhance effectiveness, continually releases tiny amounts of progesterone, a naturally occurring contraceptive hormone, into the uterine cavity.

Alza -- the only pharmaceutical manufacturer to urge physicians to obtain informed consent from prospective users -- sells about 100,000 units annually, a relatively small number. Alza, based in Palo Alto, Calif., requires annual replacement of the system.

Alza acquired a U.S. monopoly on IUDs in January 1986, when G.D. Searle & Co. halted domestic sales of its similar CU-7 and TATUM-T devices.

These have a three-year replacement cycle and use copper, as does the Copper T380A, to improve efficacy.

Searle, which attributed its action to product-liability litigation, estimated that a million American women were using its devices, and that physicians prescribed between 300,000 and 400,000 of them in 1985.

Ortho Pharmaceutical Corp. decided in September 1985 to stop making its Lippes Loop IUD.

The Johnson & Johnson subsidiary cited "economic considerations," including a steady decline in IUD use and a preference among physicians for smaller copper-containing IUDs over chemically inert devices such as the Loop.

Resistance to IUDs began increasing in mid-1974, when A.H. Robins Co. ended sales of the defective Dalkon Shield.