Rachel Hyman, a Mercer Island mother of two, was diagnosed with gestational diabetes during both her pregnancies. Because of her dietary restrictions -- no sweets and limited carbohydrates -- she wound up losing a few pounds. "Although emotionally it was difficult for me not to eat what I wanted, the diet my doctor put me on was very healthy and very balanced," Hyman says.

"Eating protein at every meal, opting for whole grains and eating small, frequent meals is what I recommend for gestational diabetes," says Loren Riccio, N.D. L.M., a naturopathic doctor and licensed midwife in Ballard. "Eating nuts or a protein snack prior to bedtime helps keep your blood sugar from dropping during the night."

Even though you may not have gestational diabetes, eating a well-balanced diet during pregnancy is one of the best things you can do for you and your baby.

Optimal pregnancies

"A pregnant woman needs extra nutrients and extra calories, but only about 300 extra calories a day," says Lola O'Rourke, a registered dietician on Bainbridge Island and spokesperson for the American Dietetic Association.

A three-ounce piece of chicken and one-half cup of vegetables equal 300 calories. During pregnancy it's important to get those calories from the right foods, like protein, because it helps with cell production, O'Rourke says. Good sources of protein are lean meats, certain fish, beans, eggs, nuts and seeds.

"Eat plenty of whole grains, fruits, vegetables, beans, soy, seeds, meats and dairy as well as fats from primarily monounsaturated sources like nuts, nut butters, olives, olive oil, canola oil and avocados," says Kathleen Putnam, M.S., R.D. and a nutrition consultant in Seattle. "There's definitely room for fun food, too."

"Moms-to-be need plenty of iron for red blood cell production and extra folic acid, which helps prevent neural tube defects like spina bifida," O'Rourke says. All women who can become pregnant, not just those who already are pregnant, should take 400 micrograms of folic acid every day.

"Often women who took birth control pills prior to conceiving have depleted their folic acid levels," Riccio notes. "This deficiency can also affect the baby's DNA, RNA (ribonucleic acid) and red blood cells." Dark, leafy green vegetables, fruits, beans, nuts and seeds are also good sources of folic acid.

Foods to avoid

Not everyone agrees on whether pregnant women should drink any caffeine, but O'Rourke says one cup a day is probably OK. Riccio, however, disagrees and believes caffeine should be banned altogether: "It contributes to lower birth weight and increases the rate of miscarriages. Caffeine elevates your heart rate and it will do the same to your baby."

Minimizing the intake of sugars and refined foods, and eliminating sushi, raw or undercooked meats, soft cheeses and deli meats is also recommended. Unpasteurized foods are potential sources of salmonella and E. coli bacteria, and should be avoided. "Choose whole unprocessed foods as much as possible," O'Rourke says.

Go fish

To learn what types of local fish should be avoided, visit the fish and shellfish guidelines at www.doh.wa.gov/ehp/oehas/EHA_fish_adv.htm. Experts agree that pregnant women shouldn't eat shark, swordfish, king mackerel and yellow tile fish. Because they live longer and are larger fish, they've had more time to eat smaller fish so their flesh contains larger amounts of mercury.

Tuna fish is a little more controversial. O'Rourke says to avoid albacore, but other tuna is OK in moderation. Riccio recommends no tuna at all because of the potential for a high level of mercury. Instead, she suggests wild salmon, which is a great source of omega-3 fatty acids, something the growing baby needs for brain development and the mom needs for lactation.

Special needs

With all this talk about how important protein is during pregnancy, how can the vegetarian mom-to-be get her fair share? Putnam, the nutrition consultant, says that vegetarian pregnancies can be very healthy if the woman follows a well-balanced, nutrition-filled diet. Just like other pregnant women, vegetarians should take a prenatal supplement to ensure they are getting adequate micronutrients. If the woman is totally vegan and omits all animal products, she will need to add a source of vitamin B12 to her diet. Possible sources include supplements, nutritional yeast, fortified cereal and fortified soy milk.

Nursing

Post-childbirth, a healthy diet continues to be important for nursing mothers. Women who breastfeed should add an additional 500 calories a day to their diet -- equivalent to a three-ounce piece of chicken, one-half cup of vegetables, one-half cup of brown rice and a piece of fruit, Riccio says.

Heather Larson is a Tacoma-based freelance writer who frequently covers pregnancy and parenting issues.