Last year a proposal to expand the food stamp program lost out in Congress because of the budget crunch, after getting off to a fast start in the House on a 336 to 83 vote.

Undaunted, a coalition of food-advocacy groups led by the Food Research and Action Center (FRAC) and the Center for Budget and Policy Priorities is gearing up for another try.

The key sponsor of last year's food stamp bill, House Budget Committee Chairman Leon E. Panetta (D-Calif.), and others are planning new food stamp proposals. They are expected to focus on the nutritional needs of low-income children.

New research appears to bolster the case for expanded benefits, according to proponents. A study by a Gallaudet University professor published by the National Bureau of Economic Research has concluded that low birthweight in newborns -- caused in part by inadequate nutrition of the mother during pregnancy and associated with physical and mental disabilities in newborns -- costs federal, state and local governments at least $370 million a year for special education.

Last year's food stamp bill sought expanded benefits for low-income families with children who must spend an especially high proportion of their income on housing, leaving less of their cash income to supplement food stamp allotments, as program rules assume they will. A provision addressing this problem for many aged families is already part of the food stamp law. Last year's bill also proposed a 2 percent increase in the normal stamp allotment.

The program currently provides food stamps to about 20 million people monthly and has a $19 billion appropriation for fiscal 1991, though if the recession deepens that might prove too little.

Rep. Tony P. Hall (D-Ohio), chairman of the House Select Committee on Hunger, may offer his own version of the food stamp bill. Hall also announced that he will sponsor separate legislation to phase in over five years a requirement that no person eligible for the government's special nutrition program for pregnant women, infants and children (WIC) will be turned away because of appropriations limits.

Under the program, those with incomes up to 185 percent of the poverty line (some states set lower cutoffs) can receive food vouchers for special foods like fortified infant formula. But because of appropriations limits, only about 4.5 million, or just over half those potentially eligible, actually receive benefits, which total about $2.2 billion annually.

Robert Fersh, executive director of FRAC, said his group will launch a campaign in March "to end childhood hunger."

"We've been engaged for three years in a rigorous door-to-door survey of child hunger at nine sites. The preliminary estimates suggest that 3.5 to 5 million children are hungry at any given time," Fersh said, and that another 4 million to 5 million children have such inadequate sources of assured food that they are "at risk" of hunger at any given time.

The principal difficulty in winning food stamp benefit increases, said Robert Greenstein, director of the Center for Budget and Policy Priorities and a former director of the Agriculture Department's Food and Nutrition Service, results from the federal budget law enacted last year.

Under the law, he said, any program changes that increase outlays beyond what would occur under existing program rules must be offset by revenue increases or cuts in other entitlement programs. And that presents an obstacle to change, Greenstein said.

For years anti-hunger groups have been arguing that inadequate nutrition for pregnant women is one cause of low birthweight, along with lack of prenatal health care, substance abuse and cigarette smoking. Low birthweight in turn is associated with high infant mortality and various disabilities in surviving children.

"Both pregnant women and newborn infants are particularly vulnerable to poor nutrition," the Department of Health and Human Services said last September in its book "Healthy People -- 2000," setting out health-improvement goals for the nation. "Nutrition is . . . vital to growth and development of infants, including brain function."

Added health costs for children of low birthweight have been studied frequently. But the added costs for special education of such children have been estimated for the first time in the study by Stephen Chaikind, associate professor of economics at Gallaudet University here, and Hope Corman of the Rider College (N.J.) economics department.

The authors concluded that after taking into account environmental factors in a child's background, "approximately 85,000 in special education programs are enrolled due to handicapping conditions that result primarily from the fact that they were born at less than 2,500 grams. Services for these children require at least $370 million in expenditures in the 1989-90 school year."

The authors said they used the most conservative estimates and counted only children age 6 to 15, although "additional costs accumulate for children over the age of 15 and under the age of 6."