Maureen Reagan, head of the American delegation to the United Nations Decade for Women conference, said yesterday that the United States had "come back with a win" out of the 12-day meeting in Nairobi.

Her upbeat remarks came after the conference agreed late last week to adopt a 357-paragaph final document on women's issues, after a move to include a clause equating Zionism with racism had been blocked.

"We think it is a first-class win for us, for women and the U.N. system as a whole," President Reagan's elder daughter said at a State Department briefing yesterday.

Last Friday, in Nairobi, she described conference moves to insert references to Zionism and racism as "an orgy of hypocrisy." She disclosed yesterday that she had been ready to lead an American walkout if the anti-Zionist language had been adopted.

In the last two U.N. women's conferences, in Mexico City in 1975 and Copenhagen in 1980, the United States refused to sign the final documents because they were dominated by political issues, notably the question of a Palestinian homeland and a call to condemn Zionism.

Yesterday, Maureen Reagan said the United States should be selective about participating in similar international conferences that are, in effect, extensions of the U.N. General Assembly.

She also criticized Western allies for failing to back up the United States at the conference. "I think the West Europeans by and large let us carry the ball a great many times when it would be very nice if they would join us," Reagan said.

However, she declared herself satisfied with the final document, called "Forward-Looking Strategies" for women until the year 2000.

Reagan said she had visited the president yesterday morning to brief him about the conference. Asked about the president's health, she said: "He's terrific."