BAGHDAD - When American soldiers get off duty in Iraq, the men usually return to their quarters, the women to theirs. But Staff Sgt. Marvin Frazier gets to go back to a small trailer with two pushed-together single beds that he shares with his wife.

In a historic but little-noticed change in policy, the Army is allowing scores of husband-and-wife soldiers to live and sleep together in the war zone -- a move aimed at preserving marriages, boosting morale and perhaps bolstering re-enlistment rates at a time when the military is struggling to fill its ranks five years into the fighting.

"It makes a lot of things easier," said Frazier, 33, a helicopter maintenance supervisor in the 3rd Infantry Division. "It really adds a lot of stress, being separated. Now you can sit face-to-face and try to work out things and comfort each other."

Long-standing Army rules barred soldiers of the opposite sex from sharing sleeping quarters in war zones. Even married troops lived only in all-male or all-female quarters and had no private living space.

But in May 2006, Army commanders in Iraq, with little fanfare, decided that it is in the military's interest to promote wedded bliss. In other words: What God has joined together, let no manual put asunder.

"It's better for the soldiers, which means overall it's better for the Army," said Command Sgt. Maj. Mark Thornton of the 3rd Infantry.

Military analysts said this is the first war in which the Army even gave the idea any serious consideration -- a reflection not only of the large number of couples sent to war this time, but also of the way the fighting has dragged on and strained marriages with repeated 12- and 15-month tours of duty.

While some couples were also sent into the 1991 Gulf War, the fighting was over before their living arrangements became an issue, said Lory Manning, a retired Navy captain who studies how military policies affect women for the nonprofit Women's Research and Education Institute.

More than 10,000 couples are in the Army. Exactly how many are serving in the war zone, and how many of those are living together, are not clear. The Army said it does not keep track.

But Frazier and his wife, Staff Sgt. Keisha Frazier, are among about 40 married Army couples living together on "Couples Row" at Camp Striker, which is on the oustkirts of Baghdad and is one of more than 150 U.S. military camps in Iraq. Similarly, a Couples Row opened in October at nearby Camp Victory, though it has trailers for only seven of the many couples who have requested them.

Husbands and wives are still prohibited from public displays of affection, under the same strict regulations that govern unmarried men and women in uniform. Holding hands and kissing, whether on duty or in the chow hall, are against the rules.

"It's rough on marriages when, over the course of years, you don't see each other," Manning said. "It would make sense, certainly from a morale perspective and for the Army, to try to preserve marriages."

The only downside of married soldiers sharing sleeping quarters, she said, would be an increased risk of pregnancies.

Whether the policy applies to troops in Afghanistan is unclear. Pentagon officials said that decision is up to individual commanders, but they did not return repeated calls for comment.

John Pike, director of the military think tank Globalsecurity.org., said: "I think they are looking under the sofa cushions for anything they can do to improve retention. They spend a lot of money getting these people trained up."

After spending the first five months of their 15-month deployment on separate bases in tents with up to 15 other soldiers, all of the same sex, the Fraziers prize the small degree of privacy and intimacy they gained after moving in together in October.

Still newlyweds, Sgt. Amanda Christopher, 25, and her husband, Sgt. Matthew Christopher, 22, said the change in rules has been a blessing for their nearly year-old marriage, four months of which has been spent in Iraq.

Both work at the military hospital in Baghdad's fortified Green Zone, where Amanda is a licensed practical nurse and Matthew is in patient administration, which can include mortuary duties.

"Some of the stuff I've seen, if she weren't here, I'd be a lot less cool about it," Matthew said as the pair sat inside their potpourri-scented living quarters -- a mere 120 square feet, with a TV set atop two black lockboxes, an impressive collection of stuffed animals and a Chicago Bears plaque. "There was one night in particular, I saw something and I just thought, 'Oh, God.' I came in here, talked to her for a few minutes, went outside, took a deep breath and I was good to go."

Because of the prohibition on public displays of affection, the Christophers declined even to put their arms around each other for a photo.

"It's not like in the civilian world where if you see your boyfriend at work you can just go, 'Oh, hi, Babe,'" Amanda said. "We're in uniform, and we have to maintain a professional demeanor at work."

Capt. Jessica Hegenbart and her husband, Chief Warrant Officer Brian Hegenbart, had to live separately for two months when they arrived at Camp Striker because all the trailers for couples were full and were mostly allotted by rank. They finally moved in together in June.

"It's nice to come back to our trailer. I just feel bad for all those guys who don't have that to come home to every day," said Brian, a 32-year-old Black Hawk helicopter pilot.

Living together, however, doesn't stop the Hegenbarts from worrying about each other's safety. Sometimes, it can make it harder.

"Because we're so close out here, we know to the hour when our loved one's supposed to be home from a mission," Jessica said. "So if they're late, our brains starts going to that place where you start to wonder what went wrong. That happens more often than I'd like to admit."