COPENHAGEN -- Take about 80 female naval recruits and distribute them, along with 300 male sailors, among seven Danish warships. Send the ships out to sea for periods ranging from several weeks to three months, and what do you get?

The answer, in part, is five pregnancies and one mid-Atlantic marriage, and a lot of fighting over shipboard bathrooms.

But a four-year Danish experiment on assigning women to naval combat duties also demonstrated that, given enough time to overcome problems of close quarters and unequal physical strength, male-female crews outperform single-sex units of either gender.

Conclusions drawn from the experiment, completed last year by the Danish Defense Command, indicated that women recruits were more highly motivated than men, and generally were rated "equal or sometimes even higher than . . . their corresponding male colleagues."

As a result of the study, the Danish parliament has authorized the recruitment of women for front-line naval assignments on an equal basis with men for all but submarine duty. A similar experiment now under way in the Army and Air Force, with women assigned to tank companies, field artillery batteries and Hawk missile squadrons, is expected to recommend ending most assignment restrictions in those service branches.

Twelve of NATO's 16 member nations have women in some capacities within their armed forces. The exceptions are Italy, Luxembourg, Spain and Iceland, which has no troops. The proportion of women varies from less than 1 percent in West Germany, Turkey and Portugal to nearly 10 percent in the United States.

All but a handful, however, including the United States, specifically exclude women from "operational" or combat assignments -- those where they would end up fighting in wartime -- as a matter of law or policy.

In theory, Denmark, Belgium, the Netherlands and Norway allow women in all assignments. But only Denmark has moved toward imposing full equality in all armed forces branches.

When the Danish experiments began, the women recruits were considered so unusual that the European media flocked to interview them. They were photographed sitting astride their missiles and stomping through forests with camouflage paint on their faces.

Eventually, the attention became so intense that the women themselves asked that there be no future interviews, command officers said. The command agreed, fearing that if the women were excessively watched, the actions of both sexes -- and the experiment -- would be skewed.

Denmark clearly prides itself on enlightenment and lack of discrimination. At the same time, full incorporation of women into the 30,000-member Danish armed forces posed potentially fewer logistical problems than similar actions in larger and more rigid military institutions.

But even the enlightened Danish male balked at the prospect of working side by side with women in some of the most grueling and potentially dangerous defense jobs.

The Air Force was fairly amenable to the program, said Susan Schlueter, a military psychologist working on the experiments. But the Navy and the Army "didn't want women," she said. The men feared that their presence would destroy what many men value most in the military -- the feeling of locker room camaraderie and male solidarity.

"They live in a society in which they see no place for women, a male world in which they want to be left to themselves," Schlueter said.

Maj. J. Storm-Christensen, secretary to the Army-Air Force project group, agreed. "The greatest problem has been the attitude of the male-dominated Army. It has always been men and only men," he said. "They say, 'It's a job for men, and we don't want women here.' "

But the military had little choice. Women were legally barred from combat assignments here until a comprehensive equal rights law was passed in 1978.

The Danish Equal Status Council, a government watchdog agency, immediately began pressing for the law to be applied to the armed forces. The Defense Ministry balked and was granted an exemption from its provisions until the mid-1980s, provided it began immediate experiments to "enhance" employment opportunities for women in the services.

The armed forces had an additional reason to go along with the experiments. Like much of Western Europe, Denmark has had a declining birth rate that threatens the future recruitment pool for its largely volunteer military.

When the naval experiment began, newspaper advertisements for women recruits initially drew about 4,000 responses. Of the 200 considered potentially qualified, about 80 passed the physical and psychological tests.

Males and females were given the same basic training, and the women were then assigned, along with men, to mine layers and missile patrol boats, as well as the fisheries-protection craft that travel as far afield as Greenland and the Faroe Islands.

To pave the way for the women sailors, Schlueter spent weeks on each of the ships chosen for the experiment. Based on her reports, it was decided that sleeping facilities aboard ship would be separate, toilets would be unisex but equipped for personal privacy and bath times would be alternated by sex.

The women were briefed on what Schlueter called the "truculent delights at sea -- the suspicion, prejudices and bad jokes with which they would inescapably be confronted." They were asked to conduct themselves in accordance with the knowledge that they would be very difficult to replace if any of them had to leave the program.

The Navy monitors considered, then rejected, suggestions that they brief men and women on potential "relationship" problems. "When two sexes work on board ship," Schlueter wrote in one preliminary report, "it is to be expected that cases of more than common sympathy arise."

No special rules were made on the subject of sexual harassment. "They're adults; don't make a fuss about it," she said. "If you expect problems, there will be problems."

It was on the fisheries-protection ships, which are at sea for up to three months at a time, that the experiment suffered "a few bad experiences," including a fistfight, and "some jealousy between men," said Cmdr. P. Toersloev.

"But it had some happy endings as well," said Maj. Kurt Broens-Hansen, referring to one mid-Atlantic wedding.

The Navy tended to treat the pregnancies as routine matters falling under existing guidelines, requiring the women, most of them in their early twenties, to be rotated to temporary administrative duty after four months.

In general, "relations between the sexes do not play as big a role as some feared, in the ships or the tanks," Toersloev said.

Among the other conclusions:

The number of women who were interested in combat jobs was much lower than expected for both the Navy and the Army. This was attributed in part to cultural programming and educational deficiencies that have provided fewer women with the basic qualifications necessary for the more mechanical and technical tasks.

In the Army experiment, many women left before completing the program, a decision officials attributed to "physical-strength requirements, the military environment and discipline, the hard training program and private matters."

The question of physical strength was found to make little difference in the Air Force. Although it caused minor problems in the Navy, "these were overcome by more careful distribution of work."

Women "seem to have the same psychological perseverance as men," the Navy report said, although "it should be mentioned that female gun crews have shown nervousness during gunnery exercises, i.e., they close their eyes when a shot is fired."

Experiments in all branches found that when left on their own to work out task divisions, mixed units tended to work more efficiently than either all-male or all-female groups. The presence of women often led men and women to become more competitive with their own and the opposite sex, leading to higher motivation.

Once they became used to each other, both men and women preferred working in mixed rather than single-sex units.

While men respond to negative pressure, women perform better with positive motivation. "If you tell a woman that she can do something better than she ever thought, she will do it," said Schlueter. "You can't yell at the women. They don't like it, and it doesn't work."