Recommendations for weight gain during pregnancy change like fashions in baby names.

In the 19th century, when maternal mortality was high and large babies meant a difficult labor, overeating during pregnancy was shunned. In the 1930s, 15 pounds was the recommended maximum. By 1970, the suggested range rose to 20 to 25 pounds.

Last month, an Institute of Medicine committee recommended that normal size women should gain even more weight during pregnancy -- 25 to 35 pounds. The latest increase reflects current medical concerns about preventing low birthweight babies who have higher rates of mortality, mental retardation and other developmental problems.

What's an expectant mother to do?

"It doesn't mean you're supposed to gorge on cheesecake and ice cream," said Gail Levey, a spokeswoman for the American Dietetic Association. "The idea behind gaining weight during pregnancy is to provide the baby with nutrients. To do that, you have to eat foods that give you the biggest bang for your buck. If you're adding more calories by eating coffee cake, you're not going to get the added amount of nutrients."

The most important message in the Institute of Medicine's report is that pregnant women should stick with the diet recommended for all healthy Americans -- one that combines low-fat dairy products, lean meats, whole grains and fruits and vegetables, said Yvonne Bronner, a nutrition professor at Howard University.

"It's not really so much that women should eat more. What we're now saying is that there's such a benefit that it's very important that you eat what you're told to eat," Bronner added.

According to the U.S. Department of Agriculture, a pregnant woman's daily diet should consist of three eight-ounce glasses of milk or other dairy products; six to seven ounces of meat, poultry or fish; six servings of fruits and vegetables, and six to 11 servings of grains, cereals and pasta. One serving is equal to one-half cup or one slice of bread.

Most pregnant women fall short of all these goals. As a result, they do not get the recommended daily intakes for eight nutrients -- folic acid, calcium, iron, zinc, magnesium and vitamins B-6, D and E. And they fall "considerably below" the recommended intakes for iron and folic acid, said Susan Welsh, director of the nutrition education division of the U.S. Department of Agriculture's Human Nutrition Information Service.

Poultry and lean red meats such as round and tenderloin are good sources of iron, magnesium and zinc. Although the iron in animal products is better absorbed than that in plant foods, absorption is enhanced by eating spinach, dried beans, peas and lentils along with a vitamin C source such as strawberries, tomato juice or orange juice.

Legumes, spinach, broccoli and orange juice are all good sources of folic acid, Levey said.

For those who don't like skim or 1 percent milk, low-fat yogurt, frozen yogurt, ice milk and puddings made with low-fat milk are good sources of calcium. Leafy vegetables such as turnip and mustard greens, kale, collards and broccoli, and canned sardines or salmon with bones are also good alternatives, Levey added.

To increase calories, simply telling pregnant women to consume a specified amount more each day is difficult, according to Roy M. Pitkin, an obstetrician-gynecologist at the University of California at Los Angeles and chairman of the committee that compiled the report. That's because everybody has different caloric needs, depending on their size, weight and activity level.

A more realistic measure is to monitor weight gain, Pitkin said. "If a woman is not gaining adequately, clearly she needs to eat more. If she's gaining excessive amounts, she needs to cut down. Use the scale to tell you what to do."

The committee also recommended that underweight women gain between 28 and 40 pounds, and obese women gain at least 15 pounds. Young adolescents and blacks, who often have smaller babies, should try to gain the higher amounts.

Women should gain about one pound per week during the second and third trimesters, and overweight women should gain at half that rate.

For underweight women, Pitkin said, the report reinforces that "weight gain is the most important thing they can do" during pregnancy. The message to normal weight women is "not to worry about gaining weight."

For women who need to gain more weight, it may simply mean eating larger portions of nutrient-dense foods, said dietitian Levey. If a pregnant woman is used to eating a lot of empty calories -- cakes and cookies that are high in energy but low in nutrients -- she may need to change the types of foods she eats as well as the amount, she said.

But pregnant women need not eliminate all "fun foods," said Levey. As Pitkin said, some "junk foods" are okay so long as they aren't replacing other foods. "If you're eating Hostess Twinkies rather than lettuce, it's not a good idea. But if you're eating Twinkies in addition to lettuce, that wouldn't be so bad."

Eating Right appears on alternate Tuesdays.