The unprecedented deployment to the Persian Gulf of single parents and couples with children is confronting the all-volunteer military with family problems it has never had before.

As parents with infants as young as a few weeks old face leaving their youngsters with grandparents, friends and babysitters, a campaign in favor of exempting one parent from the combat zone has gained support among military parents, legislators and children's advocacy groups.

But military personnel experts say such exemptions would hinder the military's effectiveness and would be unfair to enlistees who are not parents. Besides, they add, no one forced anyone to join the all-volunteer service.

Changing the rules "would weaken our combat capability by removing key personnel from our deployed units and by undermining unit cohesion and esprit de corps," Defense Secretary Richard B. Cheney and Joint Chiefs of Staff Chairman Gen. Colin L. Powell said in a letter Thursday expressing their opposition to a proposed Senate resolution directing the department to provide exemptions voluntarily.

The percentage of women in the military has grown from less than 2 percent in 1973 when the all-volunteer force was established to about 11 percent, according to the Pentagon. There are nearly 47,000 military couples with children and another 67,000 single parents, two-thirds of them men, according to figures Sen. John Heinz's (R-Pa.) office obtained from Cheney's office. Heinz introduced the resolution, which was blocked in committee.

"As a policy matter, they're in a box," said Carolyn Becraft, an expert on women in the military and consultant for the Women's Research and Education Institute. "You can't say a person can't have children and you can't say you can't be a single parent because that involves a lot of men."

The choice between family and military obligations has been an agonizing one for some parents.

Army Pfc. Sherry Kaiser, 20, of Gallatin, Tenn., said she will carry her newborn baby with her when she reports to Fort Rucker, Ala., on March 1, four months after her husband was deployed to Saudi Arabia.

"The Army seems to think I can leave her with just anybody," said Kaiser, who said her parents are unable to care for her daughter because they each work two jobs. "I'm frustrated and under a lot of stress about it. If they want to court-martial me, they'll have to, but on what grounds? That I want to take care of my baby?"

Child advocacy groups say many children fear the worst from the war -- "that they will be abandoned forever by both parents," said Mary Wright Edelman, president of the Children's Defense Fund, which supports exempting one parent from combat service and posting them instead in a location where they could take care of the children.

"We obviously have to balance the needs of children and the responsibilty of parents with the needs of the war," said Edelman. "War is an extremely stressful event for children. We just need to think about the impact on them."

The Pentagon does not know how many people deployed in Operation Desert Storm left behind children without a parent, but it is collecting the data and will release its findings at the end of the month, said Pentagon spokesman Maj. Doug Hart. The problem of caring for them appears to be "more anecdotal" than systematic, he said. "For the most part, the program is working well."

The military requires its personnel to have an up-to-date child care plan that designates a legal guardian and care provider for dependents. If the military determines that no guardian is available, it can choose to discharge the parent or place him or her at a job where they can still care for their children.

Unit commanders are often diligent in making sure the designated guardian is available and suitable. The many peacetime mobilizations that some active-duty personnel go through offers a test run for child-care designees and military parents.

But, say critics, some units rarely mobilize, some commanders are lax about enforcing the requirement and for many reservists, who never believed there would be a war in their lifetime, having a child-care plan was an empty gesture. It was an all but empty gesture for some of those designated to take the children, usually the grandparents.

"It's been rough," said Claudia Ellison of Savannah, Ga., whose daughter and son-in-law left her with 4-month-old Jamey Ransom when they deployed to Saudi Arabia. "She was breastfeeding him. When she left he would get up at night . . . and just cry. He would look around the room; I guess he was looking for Mary."

It is the demographics of the all-volunteer force and the particular nature of the gulf deployment, with its broad call-up of active and inactive reserves, that has caused the child-care problems, experts say.

While the number of parents who left their children in the care of others is expected to be a small percentage of the total, the problem appears greatest among young, first-time enlistees, said Becraft.

"They have no leverage within the system" to either pay for adequate child care or to arrange postings that let couples balance work and child care between one another, she said.

Before the war, a pregnant enlisted woman could get a discharge and expect to serve the balance of her obligation in the ready reserve, whose members do not participate in monthly exercises.

But the call-up of reservists for the gulf has changed that for some women who were discharged because they gave birth and have now been called to duty.

Jan. 22, the day Spec. 4 Faith Stewart went into labor at her parents' home in Munsy, Pa., was also the day the Army informed her she was to report for gulf duty.

With her husband, Jack, already in Saudi Arabia, Stewart, 21, will reluctantly take her baby son next week to her elderly in-laws in Florida.

"He's now only two weeks old, and there's no one here to take care of him," said Stewart, a member of the ready reserve. The Army "said there were hundreds of cases like mine throughout the U.S. and they were making few exceptions," she said. "But I feel he definitely needs to have me here."

The call-up has produced even more troubled situations for other parents and children.

Last month, Army Spec. 4 Melinda Davis was arrested by military police in Massachusetts and held for 24 hours at Fort Dix, N.J., after she failed to report to reserve duty because, she told authorities, she had no one to care for her 16-month-old. She was transferred to Aberdeen Proving Ground in Maryland, where she is working pending the disposition of her case. Her daughter is with her mother.

Three boys, ages 5 months, 2 and 4 years old, were placed temporarily in a foster home last month after authorities in Fairdale, W.Va., charged the woman who was caring for them with first-degree murder in the drowning death of her husband.

The boys' parents had left them with Demerise Ann Smith, 39, when they were deployed to the gulf, according to Raleigh County Assistant Prosecutor Kristen Keller. Their mother, Michelle Lawrence, since has been discharged for medical reasons, she said, and the children are living with her.

In the most publicized case, Staff Sgt. Faagalo Savaiki, a single parent called up in August, was arrested and charged in Clarksville, Tenn., with three misdemeanor child abuse charges for failing to properly provide for his children before reporting for gulf duty.

Savaiki's three children, ages 9, 12 and 13, were allegedly found dirty and without food. He had reportedly taped a note to the wall with instructions on how to use his automatic bank teller card to withdraw money. The children have been placed temporarily in a foster home. He has pleaded not guilty and is scheduled to stand trial Feb. 28.

Several members of Congress, including Heinz and Rep. Barbara Boxer (D-Calif.), have recently introduced bills to exempt one parent from fighting in a Persian Gulf combat or "imminent danger" zone. Military regulations have long exempted the last surviving sibling or spouse of a soldier killed in action. There are exemptions for other emergencies as well.

The separate bills give the department the right to choose which parent to exempt. Exempted parents would serve at a noncombat site where he or she could care for children. Under Boxer's bill, the department also could add to the exempted parents' service obligation the time they would have served in combat.