Army leaders have not yet learned how to cope with the growing number of women in their ranks and need special training, according to the most detailed study ever conducted by the Army on the subject.

Also, said the report just released, the Army should recognize that fraternization now includes officers dating and sometimes marrying enlisted people, a social phenomenon so widespread that new guidelines are required.

Despite that and other problems such as pregnancies, the report concluded that "the problem of utilization of female soldiers does not appear to be appreciably greater than that associated with male soldiers."

The Army's present guidelines on fraternization are designed to discourage male officers from dating female enlisted persons. But, the report noted, there are no rules or laws specifically forbidding fraternization.

"The increasing numbers and expanding roles of women in the Army," the report said, "particularly in specialities and units formerly the exclusive domain of men, have generated an assortment of troublesome social concerns loosely lumped together under the label of sex fraternization.

"Natural as it seems in view of contemporary America's liberal attitudes toward sex," the Army's report continued, "sex fraternization is seen as a clear distraction and threat to expedient mission accomplishment," especially in isolated units.

Women will remain "distractive" to men as long as they remain a small minority in the Army, the report said, and this status imposes on them "social pressures far beyond those normally endured in the civilian world.

The report said that "perhaps the most protentially dangerous form of sex fraternization [in] the Army today is dating between officers or non-commissioned-officers and enlisted women."

The study called current guidelines for such dating "inadequate," adding that "fraternization now encompasses socialization, dating, courting and marriage." The report recommended that the Army "define unacceptable fraternization."

Currently, there are 5,737 female and 77,776 male commissioned officers in the Army, or 7 percent women, and 47,374 female and 623,826 male enlisted people, or about 7 1/2 percent women. The report recommended that the number of enlisted women be increased to 75,000 by 1983, or 13 percent of total enlisted force.

The report recommended a number of steps in addition to fraternization guidelines to prepare the Army for this tremendous sociological change, including the following:

Special training in female physiology and male reaction to women soldiers and officers, because "the increasing number of women in the Army has posed new problems for male and female officers and noncommissioned officers which are foreign to their personal and professional experience and training."

Setting strength requirements for the various jobs in the Army so that women are neither frozen out of certain specialities nor given heavier tasks than they can handle.

New rules which would require discharging pregnant soldiers once a doctor determined she could not be deployed or else putting her on leave wihtout pay until physically able to return to duty.

The report, entitled "Evaluation of Women in the Military," said pregnancy is perceived in the field "as the greatest impediment to the full intregration of women in the Army." In fiscal 1977, 15 percent of women soldiers became pregnant.

At a Pentagon news conference yesterday called to discuss the report which now goes to the Army brass for consideration, two of the service's leaders expressed different views on the pregnancy issue.

Robert Nelson, assistant secretary of the Army, said pregnancy should be viewed as "temporary medical disability" which does not warrant being kicked out of the Army or being put on leave without pay on grounds that the affected troops could not be deployed with their Army units.

But Lt. Gen. DeWitt Smith Jr., the Army's personnel chief, said of the new mothers: "If a bugle is blown, they can't be babysitting."