In a break with a long-established policy, the Agency for International Development has agreed to fund groups that promote only "natural" family planning in underdeveloped countries, without reference to other available forms of contraception.

In the past, AID required all its grant recipients to supply couples with a wide choice of contraceptive methods, such as birth-control pills, intrauterine devices, spermicides and condoms.

The agency's shift means that the natural family planning advocates will be able to promote just their own method, which involves refraining from sexual intercourse during about half of a woman's menstrual cycle.

Some of the groups oppose the use of other contraceptive methods, saying that they destroy life in its earliest forms through mechanical or chemical means.

The policy change comes after a vigorous lobbying campaign by some natural family planning groups that involved Vice President Bush and former White House aide Faith Ryan Whittlesey, who is now the U.S. ambassador to Switzerland.

AID is the federal agency most involved with channeling foreign aid and information for family planning to the Third World.

The new policy will apply immediately to a $20 million AID program for five years that will promote this method.

Since 1981, AID funding for natural family planning has mushroomed from $800,000 to $7 million.

The natural family planning groups who lobbied for the change are opposed to abortion and all forms of contraception other than periodic abstinence.

They now encourage use of the so-called Billings method, in which women test their cervical mucus to determine when they are fertile and thus when they must abstain from intercourse.

But the effectiveness of the method has been challenged. A recent World Health Organization survey in El Salvador, India, Ireland, New Zealand and the Philippines found that even though 93 percent of the women were able to recognize when they were fertile, the method was only 78 percent effective because couples did not abstain from intercourse when they were supposed to.

The change in the AID policy has angered groups committed to "informed consent," the idea that people receiving family planning advice should be given information on a wide range of birth-control choices.

"For 20 years, AID has strongly supported freedom of choice in family planning programs. It has now adopted a policy that will deny women abroad freedom of choice in their method of family planning," said Kathleen Mazzocco, spokesman for the Population Crisis Committee in Washington.

But the decision has delighted the groups that lobbied for it. "I am still boggled that we won on this issue; I never expected it," said Mike Marker, co-director of the Minnesota-based Human Life Center.

Since he was appointed in 1981, AID Director M. Peter McPherson has been under pressure from conservatives and antiabortion groups. They have criticized AID for providing foreign aid to famine-struck Marxist regimes in Mozambique and Ethiopia and accused the agency of being indirectly involved in promoting abortion in China -- a charge denied by McPherson, who has repeatedly emphasized that AID promotes all forms of family planning except abortion.

According to Capitol Hill sources, pressure to change the agency's "informed-consent" policy came first in a March 13 letter to McPherson from Whittlesey, then special assistant to the president for public liaison.

Whittlesey voiced the concern of the Catholic League for Religious and Civil Rights that AID was discriminating against natural family planning organizations that were seeking agency grants.

"I would appreciate your guidance regarding these allegations since they would affect the president's credibility with the pro-life movement, which has been so supportive of the president," she wrote. "It would be unfortunate if any conflict developed between the administration's pro-life policies and its population assistance policies."

Whittlesey asked McPherson whether informed consent was an internal AID policy or required by Congress. "If NFP recipients are required to provide referrals to organizations that engage in abortion or provide chemical or mechanical techniques, we will be excluding the very groups that are more effective in promoting NFP . . . ," she wrote.

On March 15, McPherson met with representatives of antiabortion groups. Among them was Mercedes Arzu Wilson, executive director of the Family of the Americas Foundation, which lists as one of its objectives "the rejection of contraception, abortion and sterilization."

According to an internal AID memorandum, Wilson asked if AID intended to change its policy on informed consent. When McPherson said it did not, Wilson replied: "Then we are out of it."

On May 21, Wilson and Rep. Henry J. Hyde (R-Ill.), a vocal opponent of abortion, met with the vice president. On May 29, Wilson wrote Bush:

"As you so rightly commented, Mr. Vice President, the internal regulations that Mr. McPherson refuses to change are absolutely irrational and are channelling taxpayers' monies to the wrong hands."

According to Bush spokesman Shirley Green, the vice president thought that government regulations were standing in the way of a worthy goal. "He thought the policy should be reviewed," said Green, "but he did not lean on McPherson."

In mid-June, AID softened its line on "informed consent," saying that to qualify for agency funds, natural family planning groups only had to refer clients to other family planning services if they specifically asked for such information.

But on June 18, eight natural family planning groups, led by Marker and Wilson, wired McPherson to say that their "conscience" prevented them from going along with this policy.

By July 8, McPherson had altered the agency's position, saying the groups did not have to provide information on other methods.

"I struggled with this decision a lot," McPherson said last week. "It was not taken in a day. But I feel this modification is an advance of family planning overall."

He said that the policy had excluded many of the groups most knowledgeable about natural family planning from qualifying for the agency's expanded grant program in that area.

Asked if Bush had pressed him to change the policy, McPherson replied, "His office did talk to me when they referred Mrs. Wilson's letter to me. I called the vice president after I had made my decision. He said 'Fine.' "