What a woman eats and drinks during pregnancy is her baby’s main source of nourishment. So, 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.

A pregnant woman needs more calcium, folic acid, iron and protein than a woman who is not expecting, according to a study. Here is why these four nutrients are important.

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

It may be hard to get the recommended amount of folic acid from diet alone. For that reason it is recommended that women who are trying to have a baby take a daily vitamin supplement containing 400 micrograms of folic acid per day for at least one month before becoming pregnant. During pregnancy, it is advised to women to increase the amount of folic acid to 600 micrograms a day, an amount commonly found in a daily prenatal vitamin.

Food sources  fortified or enriched cereals, breads and pastas, citrus fruits, leafy green vegetables,beans.

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. 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 age 19 and over need 1,000 milligrams of calcium a day; pregnant teens, ages 14 to 18, need 1,300 milligrams daily.

Food sources: milk, yogurt, cheese, calcium-fortified juices and foods, sardines or salmon with bones, some leafy greens.

Pregnant women need 27 milligrams of iron a day, which is double the amount needed by women who are not expecting. Additional amounts of the mineral are needed to make more blood to supply the baby with oxygen. Getting too little iron during pregnancy can lead to anemia, a condition resulting in fatigue and an increased risk of infections.

To increase the absorption of iron,it is recommended to include a good source of vitamin C at the same meal when eating iron-rich foods. For example, have a glass of orange juice at breakfast with an iron-fortified cereal.

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

More protein is needed during pregnancy, but most women don’t have problems getting enough protein-rich foods in their diets. The protein is described as “a builder nutrient,” because it helps to build important organs for the baby, such as the brain and heart.

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

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

When counseling pregnant women, it is recommended 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.

Pregnant women should focus on fruits and vegetables, particularly during the second and third trimesters. These colorful foods are low in calories and filled with fiber, vitamins and minerals.

Pregnant women should include good protein sources at every meal to support the baby’s growth. Protein-rich foods include meat, poultry, fish, eggs, beans, tofu, cheese, milk, nuts and seeds.

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

Aim for 3 to 4 servings of dairy foods a day. Dairy foods, such as milk, yogurt and cheese are good dietary sources of calcium, protein and vitamin D.

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.

For women who take chewable prenatal vitamins, it is advised checking the product labels, because chewables might not have sufficient iron levels in them.

Consuming fewer than 200 mg of caffeine a day, which is the amount found in one 12-ounce cup of coffee, is generally considered safe during pregnancy, according to a 2013 study. The committee report said moderate caffeine consumption during pregnancy does not appear to contribute to miscarriage or premature birth.

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 of cooked fish and seafood a week, according to ACOG. However, they should limit albacore or “white” tuna, which has high levels of mercury, to no more than 6 ounces a week, according to ACOG. Mercury is a metal that can be harmful to a baby’s developing brain. Canned light tuna has less mercury than albacore “white” tuna and is safer to eat during pregnancy.

Avoid alcohol during pregnancy, Krieger advised. Alcohol in the mother’s blood can pass directly to the baby through the umbilical cord. Heavy use 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).

Pregnant women are at high risk for getting sick from two different types of food poisoning: listeriosis, caused by the Listeria bacteria, and toxoplasmosis, an infection caused by a parasite.

Listeria infection may cause stillbirth, miscarriage, preterm labor, and illness or even 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 pates.

A mother can pass a Toxoplasma infection on to her baby, which can cause problems such as blindness and mental disability later in life, reports the CDC. To prevent toxoplasmosis, the USDA recommends avoiding the following foods during pregnancy:

  • Rare, raw or undercooked meats and poultry.
  • Raw fish, such as sushi, sashimi, ceviches and carpaccio.
  • Raw and undercooked shellfish, such as clams, mussels, oysters and scallops.