‘Eating for Two’ — A Quick Guide to Nutrition During Pregnancy

pregnant woman with fruit and vegetables

When it comes to pregnancy, it seems like everyone has an opinion. With advice coming at you from all sides, figuring out what’s best for you and your baby can be overwhelming.

Courtney Barnes, MD, an OB/GYN at Women’s and Children’s Hospital, and licensed dietitian Ashley Peterson, MS, RDN, LD, answer some common questions and share the advice they give to expectant mothers.

Should I be eating more now that I’m pregnant?

Peterson says that the phrase “eating for two” gives women the wrong impression. At first, your body won’t even need extra calories. Below is the breakdown by trimester, along with some serving suggestions.

First Trimester: “During the first trimester you do not need to increase your calorie needs at all,” Peterson says. “Just make sure you are trying to eat a well-balanced diet, meeting hydration needs, meeting protein needs (about 70 to 80 grams per day) and taking your prenatal vitamin.”

Second Trimester: Increase your calorie intake by about 340 calories. “The additional 350 calories can be translated to the patient’s daily diet as an additional one to two servings of fat-free or low-fat dairy and an additional one- to  two-ounce protein serving,” Peterson says.

Third Trimester: Take in about 450 extra calories per day (110 more than during the second trimester). “In the third trimester, the additional 450 calories can be one to two servings of fat-free or low-fat dairy, one to two ounces of protein and one serving of whole grain bread or cereal,” Peterson says.

Keeping a food diary or using a calorie-tracking app can help keep you on track.

Where can I find reliable information on which foods to avoid?

Dr. Barnes recommends the American Congress of Obstetrics and Gynecology as a good resource for learning which foods may be unsafe for expectant mothers. Here’s what she tells her own patients: “The main foods to avoid are high-mercury fish, such as shark, swordfish, king mackerel or tilefish. Avoid undercooked foods — make sure that meats are cooked to minimum recommended internal temperatures. Avoid unpasteurized dairy products and raw uncooked foods such as sushi. Avoid hot dogs, lunch meats and cold cuts unless they are heated up prior to eating.”

Should I be taking supplements?

 “Although a prenatal multivitamin does not replace a healthy diet, it will ensure the mother is getting all of the recommended daily nutrients,” Peterson says. “I recommend all women take a prenatal vitamin with at least 600 micrograms of folic acid, even prior to conception, to prevent neural tube defects.”

Dr. Barnes also recommends that women who don’t have access to low-mercury fish add a fish oil supplement to their diets.

Am I drinking enough water?

Courtney Barnes, MD
Courtney Barnes, MD

Women typically need between two and three liters of water per day — or about eight glasses of water. Dr. Barnes says pregnant women should add about 300 milliliters of water to that, so about one to two cups more. This supports fetal blood volume, amniotic fluid and the mother’s own increased blood volume. “Most women aren’t drinking enough water when they become pregnant, so they feel like they are drinking much more in pregnancy,” Dr. Barnes says.

Good hydration helps prevent constipation, lessens the pain of contractions and aids in delivery by increasing blood volume. Dr. Barnes offers this rule of thumb: “I usually tell my patients that if they aren’t carrying around a bottle of water all the time, they are probably dehydrated.”

How much weight should I actually gain while pregnant?

“For women who start out the pregnancy underweight (body mass index of 18.5 or less), the recommended weight gain is 28 to 40 pounds,” Peterson says. “For women who begin pregnancy at a healthy BMI (18.5 to 24.9), the recommended weight gain is 25 to 35 pounds. For women who begin pregnancy at an overweight BMI (25 to 29), the recommended weight gain is 15 to 25 pounds, and for women who begin the pregnancy at an obese BMI (>30), the recommended weight gain is 11 to 20 pounds. Talk to your doctor to find out what your pre-pregnancy BMI is.”

Is it safe to lose weight during pregnancy?

“Pregnancy is not a time to diet,” cautions Dr. Barnes. “However, if I have patients who are eating healthier than the pre-pregnant state, eating the appropriate number of calories, and they are not hungry, then I don’t worry too much if they lose some weight. On the other hand, if patients are losing weight due to calorie restriction or severe vomiting, this is a cause for concern.”

Even if you are worried about your weight, cutting calories during pregnancy can keep you and your unborn child from getting all the nutrients you both need.

Peterson offers some ideas for healthy snacks below:

  • 5 to 10 whole wheat crackers with 1 to 2 ounces cheddar or mozzarella cheese
  • 1 apple or 1 banana with 2 tablespoons peanut butter
  • 4 to 6 ounces Greek yogurt with berries
  • Trail mix (mixed nuts, dried fruit, dark chocolate)
  • ½ cup low-fat cottage cheese with ½ cup fruit of choice

Should I visit a dietitian?

“It is important to meet with a registered dietitian during pregnancy if a woman has special dietary needs such as food allergies, diabetes, weight loss, hyperemesis gravidarum; follows a strict diet (vegan, gluten free, etc.); or has a history of bariatric surgery,” Peterson says. That said, “If a woman has no special circumstances relating to nutrition, it is not necessary to meet with a registered dietitian during pregnancy.”

Dr. Barnes agrees. “There are many good resources online about nutrition in pregnancy, so for most patients, basic information is readily accessible.”

If you have questions or concerns about your dietary needs during pregnancy,