A healthy pregnancy diet is important for both mom and baby, as what a woman eats and drinks during pregnancy is her baby's main source of nourishment. Experts recommend that a mother-to-be's diet should include a variety of healthy foods and beverages to provide the important nutrients a baby needs for growth and development. Here are some tips about a healthy pregnancy diet, including what to eat and what not to eat when you get pregnant — and why.

(If you are looking for a guide for how to get pregnant, Live Science has gathered tips to increase fertility.)

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Pregnancy nutrition

A pregnant woman needs more calcium, folic acid, iron and protein than a woman who is not expecting, according to the American College of Obstetricians and Gynecologists (ACOG). Here is why these four nutrients are important.

Folic acid

Also known as folate when the nutrient is found in foods, folic acid is a B vitamin (vitamin B9) and is crucial in helping to prevent birth defects in the baby's brain and spinal cord, known as neural tube defects.

It is difficult to get the recommended amount of folic acid from diet alone. For that reason the March of Dimes, an organization dedicated to preventing birth defects, recommends that women who are trying to have a baby take a vitamin supplement containing 400 micrograms of folic acid per day for at least one month before becoming pregnant. During pregnancy, the organization advises women to increase the amount of folic acid to 600 micrograms (mcg) per day — an amount commonly found in daily prenatal vitamins. This is echoed by the National Institutes of Health's Office of Dietary Supplements. Pregnant women who took a 400-microgram folic acid supplement reduced the risk of neural tube defects in their babies by 50%, according to a 2019 paper in the journal Obstetrics, Gynaecology & Reproductive Medicine.

Food sources of folic acid: leafy green vegetables, fortified or enriched cereals, breads and pastas, as well as beans and citrus fruits.

Calcium

This mineral is used to build a baby's bones and teeth. If a pregnant woman does not consume enough calcium, the mineral will be drawn from the mother's stores in her bones and given to the baby to meet the extra demands of pregnancy, according to the Academy of Nutrition and Dietetics. Many dairy products are also fortified with vitamin D, another nutrient that works with calcium to develop a baby's bones and teeth.

Pregnant women ages 19 and over need 1,000 milligrams (mg) of calcium a day; pregnant teens, ages 14 to 18, need 1,300 milligrams daily, according to ACOG.

A full-term baby's skeleton has about 1 ounce (30 grams) of calcium in it, three-quarters of which accumulates during the last trimester of pregnancy, according to a 2021 article published in journal Nutrients.

In addition to a healthy diet, pregnant women also need to take a daily prenatal vitamin to obtain some of the nutrients that are hard to get from foods alone, such as folic acid and iron, according to ACOG.

For women who take chewable prenatal vitamins, Krieger advised checking the product labels, because chewables might not contain sufficient iron levels.

Food sources of calcium: milk, yogurt, cheese, calcium-fortified juices and foods, sardines or salmon with bones, some leafy greens (kale, bok choy).

Iron

Pregnant women need 27 milligrams of iron a day, which is double the amount needed by women who are not expecting, according to ACOG. Additional amounts of the mineral are needed to make more blood in order to supply the baby with oxygen. If a pregnant woman gets too little iron, she could develop anemia, a condition resulting in fatigue and an increased risk of infections.

To increase the absorption of iron, a healthy pregnancy diet should include a good source of vitamin C with meals containing iron-rich foods, ACOG recommends. For example, have a glass of orange juice at breakfast with an iron-fortified cereal.

Food sources of iron: lean meat, poultry, fish, dried beans and peas, iron-fortified cereal.

Protein

More protein is needed during pregnancy, but most women don't have problems getting enough protein-rich foods in their diets, said Sarah Krieger, a registered dietitian and former president of the Academy of Nutrition and Dietetics in St. Petersburg, Florida. She described protein as "a builder nutrient," because it helps to build important organs for the baby, such as the brain and heart. Experts recommend pregnant women eat at least 60 grams of protein per day, according to the University of California San Francisco.

Food sources of protein: meat, poultry, fish, dried beans and peas, eggs, nuts, tofu.

Foods to eat

During pregnancy, the goal is to be eating nutritious foods most of the time, Krieger told Live Science. To maximize prenatal nutrition, she suggested emphasizing the following five food groups: fruits, vegetables, lean protein, whole grains and dairy products.

When counseling pregnant women, Krieger recommends they fill half their plates with fruits and vegetables, a quarter of it with whole grains and a quarter of it with a source of lean protein, and to also have a dairy product at every meal.

Fruits and vegetables

A healthy pregnancy diet should include lots of fruits and vegetables, particularly during a woman's second and third trimesters, Krieger said. She recommends eating from five to 10 tennis ball-size servings of produce every day. These colorful foods are low in calories and filled with fiber, vitamins and minerals.

Lean protein

Pregnant women should include good protein sources at every meal to support the baby's growth, Krieger said. Protein-rich foods include meat, poultry, fish, eggs, beans, tofu, cheese, milk, nuts and seeds. Lean meats are meats with a lower fat content and therefore a lower calorie count.

Whole grains

These foods are an important source of energy, and they also provide fiber, iron and B vitamins. At least half of a pregnant woman's carbohydrates each day should come from whole grains, such as oatmeal, whole-wheat pasta or breads and brown rice, Krieger said.

Dairy

Aim for three to four servings of dairy foods a day, Krieger suggested. Dairy foods, such as milk, yogurt and cheese, are good dietary sources of calcium, protein and vitamin D.

Detailed information on healthy food choices and quantities to include at meals can also be found in the pregnancy section of the USDA's choosemyplate.gov.

Foods to limit

Some foods should be limited while pregnant because of the effects large quantities of this food could have on the mother-to-be and/or the developing fetus.

Caffeine

Opinion is divided on whether pregnant women need to nix their cups of coffee or tea. The ACOG recommends pregnant women limit caffeine to 200 mg per day, which is the amount found in one 12-ounce (340 g) cup of coffee. They say that any relationship between caffeine and preterm birth is unclear; in addition, the ACOG says "A final conclusion cannot be made at this time as to whether there is a correlation between high caffeine intake and miscarriage."

However, some recent research suggests even that level may be tied to birth problems, such as decreased growth. For instance, a study published in 2021 in the journal JAMA Network Open found that women who drank as little as a half a cup of coffee a day had, on average, slightly smaller babies than women who didn't drink any caffeine during pregnancy. In addition, a 2020 review study, published in BMJ Evidence Based Medicine, suggested that there was no safe level of caffeine consumption for pregnant women or for those trying to get pregnant.

Fish with low levels of mercury

Fish is a good source of lean protein, and some fish, including salmon and sardines, also contain omega-3 fatty acids, a healthy fat that's good for the heart. It is safe for pregnant women to eat 8 to 12 ounces (225 to 340 g) of cooked fish and seafood a week, as long as it's not a high-mercury fish (see below), according to ACOG.

Foods to avoid

Experts might recommend moderation for some foods, but for others they warn pregnant women should avoid them altogether.

Alcohol

Avoid alcohol during pregnancy, Krieger advised. Alcohol in the mother's blood can pass directly to the baby through the umbilical cord. Heavy consumption of alcohol during pregnancy has been linked with fetal alcohol spectrum disorders, a group of conditions that can include physical problems, as well as learning and behavioral difficulties in babies and children, according to the Centers for Disease Control and Prevention (CDC). Many women drink alcohol before they know they are pregnant, and a 2021 study published in the American Journal of Obstetrics and Gynecology found that a woman's risk of losing a baby increased with each additional week of low-level alcohol exposure.

Fish with high levels of mercury

Seafood such as swordfish, shark, king mackerel, marlin, orange roughy, some types of tuna and tilefish are high in levels of methylmercury, according to the Academy of Nutrition and Dietetics, and should be avoided during pregnancy. If a person eats high-mercury fish regularly, the mercury can accumulate in their bloodstream and, if pregnant, this mercury can be passed on to a woman's baby and damage their developing brain and nervous system, said the Mayo Clinic. Canned light tuna has less mercury than albacore "white" tuna and is safer to eat during pregnancy, according to a study published in 2004 in the journal Environ Res.

Unpasteurized foods and raw meat

According to the USDA, pregnant women are at high risk of getting sick from two different types of food poisoning: listeriosis, caused by the Listeria bacteria, and toxoplasmosis, an infection caused by the Toxoplasma gondii parasite.

Listeriosis is about 20 times more common in pregnant women than in the rest of the population, according to a study published in the journal Reviews in Obstetrics and Gynecology. The CDC says that Listeria infection may cause miscarriage, stillbirth, pre-term labor, and illness or death in newborns.

To avoid listeriosis, the USDA recommends avoiding the following foods during pregnancy:

Unpasteurized (raw) milk and foods made from it, such as feta, Brie, Camembert, blue-veined cheeses, queso blanco and queso fresco. Pasteurization involves heating a product to a high temperature to kill harmful bacteria. Hot dogs, luncheon meats and cold cuts, unless heated to steaming hot before eating to kill any bacteria. Store-bought deli salads, such as ham salad, chicken salad, tuna salad and seafood salad. Unpasteurized refrigerated meat spreads or pâtés.

Toxoplasmosis

A mother can pass a Toxoplasma infection on to her baby, which can cause problems such as blindness and mental disability later in life, the CDC reported. Most women are asymptomatic, according to a study published in the journal Pathogens. To prevent toxoplasmosis, the USDA recommends avoiding the following foods during pregnancy:

Rare, raw or undercooked meats and poultry. Food containing raw fish, such as sushi, sashimi, ceviches and carpaccio.Raw and undercooked shellfish, such as clams, mussels, oysters and scallops.Cats are also a source of Toxoplasma. Cats can contract the parasite by eating infected birds, rodents or other small animals, and then transmit the parasite through their feces. Older cats are less likely to shed the parasite if they have been previously infected. While the CDC does not suggest that you should give away your cat, it recommends that you:

Do not get a new cat while pregnant, and avoid stray cats, especially kittens.Ask someone else to change the cat's litter, which should be done daily. (If no one can do it for you, wear disposable gloves and wash your hands afterwards.)Wear gloves when gardening to reduce the risk of coming into contact with infected feces.Do not feed raw meat to your cat — opt instead for commercial cat food.Keep your cat indoors.

Food poisoning

Some foods may increase a pregnant woman's risk for other types of food poisoning, including illness caused by Salmonella and E. coli bacteria. Foodsafety.gov lists these foods to avoid during pregnancy:

Raw or undercooked eggs, such as soft-cooked, runny or poached eggs.Foods containing undercooked eggs, such as raw cookie dough or cake batter, tiramisu, chocolate mousse, homemade ice-cream, homemade eggnog, or Hollandaise sauce. Raw or undercooked sprouts, such as alfalfa or clover.Unpasteurized juice or cider.

Weight gain during pregnancy

Pregnancy diet misconceptions and weight gain during pregnancy

"Weight gain during pregnancy often has an ebb and a flow over the nine months," Krieger said. It's hard to measure where pregnancy weight is going, she said, adding that a scale does not reveal whether the extra pounds are going to a woman's body fat, baby weight or fluid gains.

When it comes to pregnancy weight gain, Krieger advises mothers-to-be to look at the big picture: During regular prenatal checkups, focus on the fact that the baby is growing normally rather than worrying about the number on a scale.

The total number of calories that are needed per day during pregnancy depends on a woman's height, her weight before becoming pregnant, and how active she is on a daily basis. In general, underweight women need more calories during pregnancy; overweight and obese women need fewer of them.

The Institute of Medicine (IOM) guidelines for total weight gain during a full-term pregnancy recommend that:

Underweight women, who have a body mass index (BMI) below 18.5, should gain 28 to 40 lbs. (12.7 to 18.1 kilograms).Normal-weight women, who have a BMI of 18.5 to 24.9, should gain 25 to 35 lbs. (11.3 to 15.9 kg).Overweight women, who have a BMI of 25.0 to 29.9, should gain 15 to 25 lbs. (6.8 to 11.3 kg).Obese women, who have a BMI of 30.0 and above, should gain 11 to 20 lbs. (5 to 9.1 kg). Rate of weight gain

The IOM guidelines suggest that pregnant women gain between 1 and 4.5 lbs. (0.5 to 2 kg) total during their first trimester of pregnancy. The guidelines recommend that women who are underweight or have normal weight gain, on average, about 1 pound every week during their second and third trimesters of pregnancy, and that women who are overweight or obese gain about half a pound (225 g) every week in their second and third trimesters of pregnancy.

Twins

The IOM guidelines for pregnancy weight gain when a woman is having twins are as follows:

Underweight: 50 to 62 lbs. (22.7 kg to 28.1 kg)Normal weight: 37 to 54 lbs. (16.8 to 24.5 kg)Overweight: 31 to 50 lbs. (14.1 to 22.7 kg)Obese: 25 to 42 lbs. (11.3 to 19.1 kg)

Pregnancy diet misconceptions

Are you really eating for two?

When people say that a pregnant woman is "eating for two," it doesn't mean she needs to consume twice as much food or double her calories.

"A woman is not eating for two during her first trimester," Krieger said. During the first three months, Krieger tells women that their calorie needs are basically the same as they were before pregnancy.

Krieger typically advises pregnant women to add 200 calories to their usual dietary intake during the second trimester, and to add 300 calories during their third trimester when the baby is growing quickly.

Avoid morning sickness by not eating?

When a mother-to-be is experiencing morning sickness, the biggest mistake she can make is thinking that if she doesn't eat, she'll feel better, Krieger said.

The exact causes of morning sickness are not known, but it may be caused by hormonal changes, according to the Mayo Clinic. This common complaint can bring on waves of nausea and vomiting in some women, especially during the first three months of pregnancy.

And "it's definitely not happening only in the morning," Krieger said. "It's any time of day." To ease morning sickness, it's better to eat small amounts of foods that don't have an odor, because smells can also upset the stomach, she said.

Are food cravings real?

It is common for women to develop a sudden urge or a strong dislike for a food during pregnancy. Some common cravings are for sweets, salty foods, red meat or fluids, Krieger said. Often, a craving is a body's way of saying it needs a specific nutrient, such as more protein or additional liquids to quench a thirst, rather than a particular food, she said.

This article is for informational purposes only and is not meant to offer medical advice.

Additional resources

The Institute of Medicine has a BMI calculator to help pregnant women figure out the right amount of weight to gain. Find answers to frequently asked questions about nutrition during pregnancy from the American College of Obstetricians and Gynecologists.Learn about safe food choices and food safety risks from the Academy of Nutrition and Dietetics.Editor's note: This reference page was updated on April 24, 2021, by Live Science contributor Sarah Wild.