In February this year, unconscious of the possible consequences, my husband and I and two children, a 1-year-old girl and a 4-year-old boy, moved to the United States after five years in Egypt. I was relieved that we would no longer be facing the daily threats of amoebic dysentery and salmonella, and the yearly epidemic of meningitis.

Four days after we arrived, however, I hauled my son, Adam, into the emergency room of Fairfax Hospital. He had pneumonia and it was only the beginning of a long and difficult adjustment period during which he had four asthma attacks and seemed to be constantly grieving. Only weeks ago, he remarked that he has two mothers. One, our Egyptian housekeeper, is still in Cairo.

Although psychiatrists say there is no scientific data on how American expatriate children adapt when they return to the United States, doctors say some children can expect severe problems that range from physical illness to depression, grief and a feeling of alienation from American society.

The findings, based on the unquantified observations of health care professionals, contradict the common wisdom that a return to one's native land is no chore at all.

Mental health professionals know that a move is often stressful depending on the age of the child and the situation of the family and its members. A move across cultures can be even more difficult than a move within the United States because the loss is not confined to relationships but involves a major change in lifestyle including dress, language, customs and daily routine.

"Changes in customs bring a lot of confusion" even if you're moving back to your own country, says Peter S. Jensen, chief of the child and adolescent disorders research branch at the National Institute of Mental Health. "There are new customs to deal with. The rules for play aren't the same. You're grieving and then new demands are put on you."

"You don't get any preparation for moving back," says Col. William Klein, chief of child psychiatry at the Walter Reed Medical Center, speaking of orientation seminars that could be offered to military families moving back to the United States but are not. "Going home is a fantasy, like going back to the womb. It's assumed you'll work it out."

Of the several hundred thousand American children living overseas, most are military kids living in West Germany. Tens of thousands of military children return to the U.S. each year. According to the State Department's office of medical clearance, about 4,600 children of American diplomats currently make their homes abroad. From June 1989 to June 1990, almost 600 State Department kids returned to the United States. More than 3,000 other American children living abroad belong to parents working for AID, USIA, and other government departments, and a good percentage of them are transferred back each year. To these should be added the children of businessmen, journalists and academics who return when foreign tours are over.

Interviews with parents whose families recently returned to the States confirmed the opinions of mental health professionals who point out that children who have been immersed in a foreign culture tend to suffer more when they come back to the States than children who have been sheltered by an American infrastructure overseas.

This means that American children of cross-cultural parents who have been living in the country of the foreign spouse will likely suffer more because they have made close ties abroad. School age kids and adolescents will suffer more than infants who are mostly at home with their parents and therefore insulated.

"A child of 2 is in the home," says Jensen, who has studied the effects of moving on military families. "A child of 6 is in school. Overseas he might not have circle time, reading in English, snacks, sharing, or the way privacy is respected here. Disciplinary arrangements could be different."

Military kids are generally more insulated from the stress of a cross-cultural move because most have lived in an American environment overseas. Children of business people, diplomats and journalists are more vulnerable because typically they have been more involved in foreign life.

A move from a country that has warm human and family ties and where the Americans would likely have had a nanny, could be particularly troublesome because the nanny, who has been a second mother, is often replaced in the United States by impersonal day care.

In my situation, my son, a dual national, had close ties to Egyptians. In one fell swoop, he lost his nanny, his main nurturer, and was dropped into preschool. I was totally unprepared for what would happen. He had never had asthma before. His emotional state was fragile. He cried when we watched home videotapes of him and his nanny and parents at a sporting club in Cairo and constantly seemed to be grieving.

Ashton Douglass and her husband, an AID official, who returned to the Washington area one year ago after 10 years abroad -- in Nepal and then Indonesia -- also suffered.

When the Douglass family left Nepal for Jakarta, their son Cameron, then 3, "dropped a curtain" over his Nepalese period, says Ashton Douglass. "He wouldn't talk about Nepal or speak the language. At 3 1/2, he couldn't cope," she says.

In contrast, her daughter Sarah encountered adjustment problems when the family returned to the United States from Indonesia last year. Soon after returning to this country, Sarah, 14, kept coming down with strep throat infections and migraine headaches. She was sick so often that doctors began testing for a brain tumor. Eventually, they attributed her illnesses to a lack of immunity to certain germs in the United States and to the stress of an unwanted move.

"Basically, Sarah wanted to go back to Jakarta," says Douglass. "In Jakarta, she spent most of every day in a multicultural environment. Here there's much less openness to differences. She's met kids at school but nobody she was comfortable with because her experiences were so different. If she had found one person she felt comfortable with it would have made all the difference."

An adolescent returning to the States -- even a military kid -- might be totally ignorant of the current fads, like Ninja Turtles, which would set her apart from her new American peers.

"Adolescence can be the worst," says Klein. "The child is in essence leaving the family. Peer group support is most important for that."

Although the reasons for stress in a cross-cultural move are different from a move within the United States, the manifestations, professionals say, are the same.

A child can become depressed, pick on siblings more and become more "oppositional" to his parents, says Jensen.

The role of the parent, say experts, is crucial.

"If the family helps the child grieve, that could be important for the child's development," says Klein. "You have to acknowledge that the loss occurred, not sweep it under the table."

Jensen says a parent should help a young child put his feelings to words.

Otherwise, experts advise parents to try and maintain continuity with the lifestyle and routine that existed overseas. That means not leaving a child in a day care center for 10 hours a day when, overseas, he only attended one for three hours and then came home to his nanny and friends.

Other suggestions:

Parents should invite neighborhood children over as soon as possible to meet and play with their kids.

They should let their child participate in arranging his new room.

They could circle a date on the calendar as a target for a return visit overseas. This would emphasize that the separation is not a finality.

Contact with overseas friends should be maintained.

Keep up the foreign language learned while overseas, if possible, advises Ellen Galinsky, an educator and coauthor of "The Preschool Years."

For Cathy Cowles and her husband, David, and three children, the adjustment after six years in Kenya and Egypt was easy. They decided to bring their Egyptian nanny, Mona, with them to Potomac where they settled, thus avoiding long hours of day care. The lifestyle they had in Egypt was continued in the Washington area.

The elementary school attended by their older children has encouraged talk of foreign lands, making the children feel proud of their exotic experience. "The school brought their foreign experience out," says Cathy Cowles. "The kids were able to talk about their experiences in Egypt. They brought in artifacts from foreign countries."

Psychiatrists and educators point out that a healthy child and adolescent will swiftly adopt the going mores and assimilate the fads as a way of fitting in and that parents should not be disturbed when, all of a sudden, their children, who a few weeks ago were speaking Swahili, begin chatting about Batman or Ninja turtles.

"Kids take on the externals to cope with the internals," says Galinsky. "It's a way of trying to assimilate the newness."

"A flexible, savvy kid will go ahead and accept the local environment," says Klein. "Those are skills that have been learned a long time ago in the family.

Above all, Jensen says parents should not feel remorseful about their foreign experience even if the children suffer during the move home.

"You dig in and realize there'll be a readjustment," he says. "Those kids who have moved around early on are more flexible, adjustable. And it's not particularly harmful to them in the long run."