Eating well during pregnancy is more than simply increasing how much you eat. You must also consider what you eat.

Although you need about 300 extra calories a day — especially later in your pregnancy, when your baby grows quickly — those calories should come from nutritious foods so they can contribute to your baby's growth and development.

Eating Well When You're Pregnant

Do you wonder how it's reasonable to gain 25 to 35 pounds (on average) during your pregnancy when a newborn baby weighs only a fraction of that? Although it varies from woman to woman, this is how those pounds may add up:

• 7.5 pounds: average baby's weight
• 7 pounds: extra stored protein, fat, and other nutrients
• 4 pounds: extra blood
• 4 pounds: other extra body fluids
• 2 pounds: breast enlargement
• 2 pounds: enlargement of your uterus
• 2 pounds: amniotic fluid surrounding your baby
• 1.5 pounds: the placenta

Of course, patterns of weight gain during pregnancy vary. It's normal to gain less if you start out heavier and more if you're having twins or triplets — or if you were underweight before becoming pregnant. More important than how much weight you gain is what makes up those extra pounds.

When you're pregnant, what you eat and drink is the main source of nourishment for your baby. In fact, the link between what you consume and the health of your baby is much stronger than once thought. That's why doctors now say, for example, that no amount of alcohol consumption should be considered safe during pregnancy.

The extra food you eat shouldn't just be empty calories — it should provide the nutrients your growing baby needs. For example, calcium helps make and keep bones and teeth strong. While you're pregnant, you still need calcium for your body, plus extra calcium for your developing baby. Similarly, you require more of all the essential nutrients than you did before you became pregnant.

Nutrition for Expectant Moms

A healthy diet includes proteins, carbohydrates, fats, vitamins, minerals, and plenty of water. The U.S. government publishes dietary guidelines that can help you determine how many servings of each kind of food to eat every day. Eating a variety of foods in the proportions indicated is a good step toward staying healthy.

Food labels can tell you what kinds of nutrients are in the foods you eat. The letters RDA, which you find on food labeling, stand for recommended daily allowance, or the amount of a nutrient recommended for your daily diet. When you're pregnant, the RDAs for most nutrients are higher.

Here are some of the most common nutrients you need and the foods that contain them:

Important Nutrients

Scientists know that your diet can affect your baby's health — even before you become pregnant. For example, recent research shows that folic acid helps prevent neural tube defects (including spina bifida) from occurring during the earliest stages of fetal development — so it's important to consume plenty of it before you become pregnant and during the early weeks of your pregnancy.

Even though many foods, particularly breakfast cereals, are fortified with folic acid, doctors now encourage women to take folic acid supplements before and throughout pregnancy (especially for the first 28 days). Be sure to ask your doctor about folic acid if you're considering becoming pregnant.

Calcium is another important nutrient. Because your growing baby's calcium demands are high, you should increase your calcium consumption to prevent a loss of calcium from your own bones. Your doctor will also likely prescribe prenatal vitamins for you, which contain some extra calcium.

Your best food sources of calcium are milk and other dairy products. However, if you have lactose intolerance or dislike milk and milk products, ask your doctor about a calcium supplement. (Signs of lactose intolerance include diarrhea, bloating, or gas after eating milk or milk products. Taking a lactase capsule or pill or using lactose-free milk products may help.) Other calcium-rich foods include sardines or salmon with bones, tofu, broccoli, spinach, and calcium-fortified juices and foods.

Doctors don't usually recommend starting a strict vegan diet when you become pregnant. However, if you already follow a vegan or vegetarian diet, you can continue to do so during your pregnancy — but do it carefully. Be sure your doctor knows about your diet. It's challenging to get the nutrition you need if you don't eat fish and chicken, or milk, cheese, or eggs. You'll likely need supplemental protein and may also need to take vitamin B12 and D supplements.

To ensure that you and your baby receive adequate nutrition, consult a registered dietitian for help with planning meals.

Food Cravings During Pregnancy

You've probably known women who craved specific foods during pregnancy, or perhaps you've had such cravings yourself. Some old theories held that a hunger for a particular type of food indicated that a woman's body lacked the nutrients that food contains. Although this turned out not to be so, it's still unclear why these urges occur.

Some pregnant women crave chocolate, spicy foods, fruits, and comfort foods, such as mashed potatoes, cereals, and toasted white bread. Other women crave non-food items, such as clay and cornstarch. The craving and eating of non-food items is known as pica. Consuming things that aren't food can be dangerous to both you and your baby. If you have urges to eat non-food items, notify your doctor.

But following your cravings is fine as long as you crave foods that contribute to a healthy diet. Often, these cravings let up about 3 months into the pregnancy.

Food and Drinks to Avoid While Pregnant

No level of alcohol consumption is considered safe during pregnancy. Also, check with your doctor before you take any vitamins or herbal products. Some of these can be harmful to the developing fetus.

And although many doctors feel that one or two 6- to 8-ounce cups per day of coffee, tea, or soda with caffeine won't harm your baby, it's probably wise to avoid caffeine altogether if you can. High caffeine consumption has been linked to an increased risk of miscarriage and other problems, so limit your intake or switch to decaffeinated products.

When you're pregnant, it's also important to avoid food-borne illnesses, such as listeriosis and toxoplasmosis, which can be life threatening to an unborn baby and may cause birth defects or miscarriage. Foods to steer clear of include:

• soft, unpasteurized cheeses (often advertised as "fresh") such as feta, goat, Brie, Camembert, and blue cheese
• unpasteurized milk, juices, and apple cider
• raw eggs or foods containing raw eggs, including mousse and tiramisu
• raw or undercooked meats, fish, or shellfish
• processed meats such as hot dogs and deli meats (these should be thoroughly cooked)
• fish that are high in mercury, including shark, swordfish, king mackerel, or tilefish

If you've eaten these foods at some point during your pregnancy, try not to worry too much about it now; just avoid them for the remainder of the pregnancy. If you're really concerned, talk to your doctor.

More About Fish

Fish and shellfish can be an extremely healthy part of your pregnancy diet — they contain beneficial omega-3 fatty acids and are high in protein and low in saturated fat. But limit the types of fish you eat while pregnant because some contain high levels of mercury, which can cause damage to the developing nervous system of a fetus.

Mercury, which occurs naturally in the environment, is also released into the air through industrial pollution and can accumulate in streams and oceans, where it turns into methylmercury. The methylmercury builds up in fish, especially those that eat other fish.

Because canned albacore (or white) tuna and tuna steaks are generally considered to be higher in mercury than canned light tuna, the U.S. Food and Drug Administration (FDA) recommends that you eat no more than 6 ounces a week. A 2006 review by Consumer Reports, though, showed that some canned light tuna can contain mercury levels even higher than that of white tuna, and recommends that pregnant women eat no canned tuna. But the FDA stands by its current recommendations, saying that the levels are safe if tuna consumption is limited.

It can be confusing when recommendations from trusted sources differ. But since this analysis indicates that amounts of mercury in tuna may be higher than previously reported, some women may want to eliminate tuna from their diet while pregnant or when trying to become pregnant.

Almost all fish and shellfish contain small amounts of mercury, but you can safely eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury, such as salmon, shrimp, clams, pollock, catfish, and tilapia.

Talk with your doctor if you have any questions about how much — and which — fish you can eat.

Managing Some Common Problems

Because the iron in prenatal vitamins and other factors may cause constipation during pregnancy, try to consume more fiber than you did before you became pregnant. Try to eat about 20 to 30 grams of fiber a day. Your best sources are fresh fruits and vegetables and whole-grain breads, cereals, or muffins.

Some people also use fiber tablets or drinks or other high-fiber products available at pharmacies and grocery stores, but check with your doctor before trying them. (Don't use laxatives while you're pregnant unless your doctor advises you to do so. And avoid the old wives' remedy — castor oil — because it can actually interfere with your body's ability to absorb nutrients.)

If constipation is a problem for you, your doctor may prescribe a stool softener. Be sure to drink plenty of fluids, especially water, when increasing fiber intake, or you can make your constipation worse. One of the best ways to avoid constipation is to get more exercise. You should also drink plenty of water between meals each day to help soften your stools and move food through your digestive system. Sometimes hot tea, soups, or broth can help. Also, keep dried fruits handy for snacking.

Some pregnant women find that broccoli, spinach, cauliflower, and fried foods give them heartburn or gas. You can plan a balanced diet to avoid these foods. Carbonated drinks also cause gas or heartburn for some women, although others find they calm the digestive system.

If you're frequently nauseated, eat small amounts of bland foods, like toast or crackers, throughout the day. If nothing else sounds good, try cereal with milk or a sweet piece of fruit. To help combat nausea, you can also:

• Take your prenatal vitamin before going to bed after you've eaten a snack — not on an empty stomach.
• Eat a small snack when you get up to go to the bathroom early in the morning.
• Suck on hard candy.

How to Know You're Eating Well

The key is to eat foods from the different food groups in approximately the recommended proportions. If nausea or lack of appetite cause you to eat less at times, don't worry — it's unlikely to cause fetal harm because your baby gets first crack at the nutrients you consume.

And although it's generally recommended that a woman of normal weight gain about 25 to 35 pounds during pregnancy (most gain 4 to 6 pounds during the first trimester and 1 pound a week during the second and third trimesters), don't fixate on the scale. Instead, focus on eating a good variety and balance of nutritious foods to keep both you and your baby healthy.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: May 2013