14 Healthy Eating During Pregnancy Might Be Difficult

As we have discussed in previous chapters, there are various nutritional recommendations for pregnant women. While women may initially accept these recommendations and plan to implement them as they prepare for pregnancy, they often experience multiple barriers such as nausea, vomiting, constipation, cravings, and various food restrictions that can minimize their efforts.

The mother might find that she is not able to stomach foods she normally enjoys but finds herself craving nonfood items such as ice or dirt. Hormonal changes as well as deficiencies can fuel these changes in eating patterns. The mother’s diet may also need to be modified in order to protect the fetus by utilization of proper food safety measures or omitting certain foods from her diet during pregnancy.

All of these diet modifications can make it difficult for mothers to eat a well balanced diet during their pregnancy. It is important to acknowledge these difficulties and use strategies to reduce their negative effects in order to support healthy pregnancy weight gain and minimize development issues.


You Will Learn:

  • Pregnant women should follow similar eating pattern than non-pregnant women.
  • Pregnant women may experience multiple barriers to healthy eating:
    • Nausea and vomiting might be triggered by raising hormone blood levels.
    • Progesterone causes the gastrointestinal musculature to relax leading to an increase of acid reflux and constipation.
  • Cravings and aversions are common in pregnancy but it is unclear if these are true physiological changes with a physiological purpose.
  • Pregnant women are at a higher risk for foodborne illnesses. Some can harm the fetus severly.
    • Basic food safety measures are important.
    • Pregnant women should not eat uncooked or undercooked meat, dairy and fish.
    • Alcohol and excessive caffeine intake may cause problems during and after pregnancy.


Pregnant Women Should Follow Similar Eating Patterns Than Non-Pregnant Women


We established during the last chapters that women should follow the same nutrient-dense eating pattern than non-pregnant women. this includes the healthy US eating pattern (MyPlate), the DASH diet, the Mediterranean diet and the healthy vegetarian diet. Low-carbohydrate diet need to be adjusted by increasing carbohyrate intake. Very-low carbohydrate diets such as the Keto diet are iinadequate for pregnany.

On top of that pregnant women should take a pre-natal supplement that ensures optimal folate, iron intake. Women who don’t spend sufficient time outside need a 10 µg vitamin D supplement. Iodized salt should be used when preparing foods and vegan women must take a vitamin B12 supplement or eat sufficient amounts of vitamin B12 fortified foods.

Additional energy needs during the second (+ 340 kcal) and third trimester (+ 452 kcal) are small and should come from the same nutrient-dense foods the woman is already eating.

Does that mean pregnant women can’t have and sweets and treats? The Dietary Guidelines recommend that pregnant women eat 85 % of their daily energy intake as nutrient-dense, healthy, fresh foods. This leaves 15 % of the daily energy intake for sweets and treats. If a women consumes 2000 kcal in her first trimester 300 kcal are for the sweets and treats category. During the third trimester this amount goes up to 370 kcal. 1/2 cup gelato has for example 218 kcal, fifteen potato chips have 160 kcal, two choclate chip cookies 140 kcal.

National surveys in the US give us an idea what pregnant women are eating:


The good news is that pregnant women are eating better than non-pregnant women as you see on the left side of the infographic. What does that number mean though. The healthy eating index or HEI compares an eating pattern against the Dietary Guidelines recommendations. The index ranges from 0 (lowest adherence) to 100 (highest adherence). When you look at the average score the HEI goes from 54 to 63 and that tells us that there is a lot of improvement possible.

The majority of pregnant women exceed the recommended limit for added sugar, saturated fat and sodium. These numbers always indicate that most US pregnat women eat more processed foods than a healthy, nutrient-dense eating pattern.

Looking closer at food groups pregnant women almost meet the fruit recommendation but vegetable intake is too low. Look at the graphs on the right. The light blue area indicates the intake amounts we would like to see and the purple dots is the average intake by pregnant women in the US. Women do a good job with leafy green but lack in red and orange vegetables. Living in an environment that vilifies carbohydrates it is not surprising that women do not eat enough legumes (beans, peas, lentils) and starchy vegetables.

Looking at the grain intake, which is important to provide a constant flow of glucose to the fetus, we see that the grain intake is sufficient but women need to eat more whole grains and less refined grains. this is important because whole grains and legumes from the vegetable group provide great amounts of non-soluble fiber. As you will see later in this chapter pregnant women are prone to develop constipation. A sufficient fiber intake will ensure goo gut motility.

Lastly, pregnant women get sufficient amounts of protein but we would like to see an increased intake of seafood because fatty fish is such a good source of omega-3 fatty acids needed for brain development.



Pregnant Women May Experience Multiple Barriers to Healthy Eating

The recommendations are clear for pregnancy but healthy eating is not always possible.

Pregnant women experience an initial increase of hCH and progesterone during the first trimester of pregnancy and then a continuous increase of estradiol and progesterone. These hormones do not only sustain pregnancy, adapt the woman to the demands of pregnancy, and promote placenta and fetal growth, but also impact the gastrointestinal tract in various ways.

Four of the most recognizable pregnancy symptoms involved with the GI tract are nausea, vomiting, hyperemesis gravidarum, acid reflux, and constipation. In general, these conditions are not tied with negative pregnancy outcomes, but they can certainly be unpleasant for the mother and influence her food choices throughout pregnancy.


Morning Sickness Can Make Healthy Eating Difficult Or Impossible


Nausea and vomiting of pregnancy (NVP) is one of the most common experiences women have in their first trimester. Around 70% of pregnant women experience NVP during the first trimester.  It is commonly referred to as “morning sickness,” but women may experience it at any time of the day. While NVP often improves by the start of the second semester, it can cause issues in choosing nutrient dense foods. Women may find bland foods to be a better option than greasy or spicy foods which can aggravate the stomach. It is also important to manage fluid intake to prevent dehydration.

It is unclear which exact hormones or environmental factors contribute to NVP. One prime suspect is hCG since this early pregnancy hormone declines along with the NVP symptoms. Estradiol is also discussed along with a psychological pre-disposition.

However, NVP is associated with a stable pregnancy and positive pregnancy outcomes. This may be due to higher hormone levels that stabilize the pregnancy.

Severity of symptoms varies from woman to woman and symptoms tend to peak by week 9. For most women, dietary and lifestyle treatment is sufficient. The first line of defense is avoiding stimuli—taste, strong smells, heat, noise—that trigger the nausea. While dietary recommendations are based more on observations, small meals and avoiding spicy, fatty foods is recommended. Vitamin B6 supplements and antiemetic drugs are prescribed if the woman does not tolerate symptoms well.



A majority of pregnant women experience regular NVP. However, in 0.3–2% of pregnancies, excessive vomiting known as hyperemesis gravidarum can occur. This can cause loss of hydrochloric acid from the stomach which may ultimately lead to electrolyte imbalances of chloride, sodium, and potassium.

Women may lose weight and become dehydrated because of the excessive vomiting and inability to keep any food or fluids down. It is clear that maternal weight loss should be minimized because it is an independent predictor of poor fetal outcome. However, there is current conflicting data about HG and its overall effect on birth weight.

Regardless of the effect on the pregnancy outcome, hyperemesis gravidarum is an unfortunate experience for the mother. Similar to nausea and vomiting recommendations, it may be helpful to consume smaller, frequent meals and increase resting. Medical treatment may also be necessary to correct deficiencies and hydration status.


Rising Progesterone Levels Relax the Gastrointestinal Muscle Increasing Acid Reflux and Constipation

There are various factors contributing to acid reflux in pregnant women including hormonal changes and the fetus pressing against the stomach. Acid reflux or heartburn happens when the muscles between the esophagus and stomach relax which allows the stomach’s contents to come back up through the esophagus. This may cause a burning sensation. Acid reflux is normal and usually one of the earliest symptoms of pregnancy.

Pregnancy hormones especially progesterone cause the muscles in the GI tract to relax. The relaxation of muscles can cause food to move slower throughout the GI tract which can result in increased stomach acid and an increase in heartburn occurrence. While heartburn may not be pleasant for the mother, the slow movement of food through the GI tract can be beneficial for the baby because it allows more nutrients to be absorbed which results in better nutrient availability for the placenta and fetus.



Progesterone relaxes GI muscles and reduces gut motility. This slows down digestion and allows for better nutrient absorption which includes water reabsorption in the colon. This situation contributes to constipation during pregnancy. During late pregnancy, the growing fetus and uterus press against the GI track slowing down digestion.

It doesn’t help that many American women lack fiber from fruits, vegetables, whole grains and legumes. Fiber tends to bind water and keep the stools soft.

Other dietary factors contributing to constipation are low hydration due to vomiting and iron supplements.  Physical activity tends to decrease during late pregnancy aggravating the constipation issue.

Increasing fiber consumption, fluid intake, and physical activity are recommended for smoother digestion. Fiber will help bind water, keep the stool soft, and stimulate GI motility moving the bolus forward. It is recommended to consume 25-30g of dietary fiber per day. Fiber is most abundant in fresh fruits, vegetables, whole grain breads, and legumes.

Moderate exercising will also help food pass through the body by stimulating the bowels to move. It is recommended to exercise at least three times per week for 20-30 minutes.


Pregnancy Cravings and Aversions Impact Nutritional Choices


Food cravings and aversions are another often reported feature of pregnancy. Scientifically it is not even clear they exist.

Potential hypotheses discussed, are a change of taste threshold due to the pregnancy hormones. Some pregnant women might experience bitter taste more intensely. Anecdotal evidence points toward a heightened sense of smell which would also change taste.

Hormonal changes affect women in a variety of ways during pregnancy and may also influence their food preferences. Leptin blood levels increase in the first trimester when adipose tissue is built and produced in the placenta. The levels peak during the second, and early third semester, which seems to reduce the threshold for sweet taste. Immune system changes also seem to be involved in cravings and aversions.

Food cravings and aversions often go hand-in-hand with nausea and vomiting in early pregnancy. Women may have increased cravings for dairy products or carbohydrate rich foods such as crackers, breads, ice cream, and fruits. Some may find they cannot tolerate caffeine or greasy foods. They may also have aversions towards strong tasting or smelling foods. These may act as a  bodily defense mechanism as the woman craves sources of glucose which are necessary for fetal development.

Some women may experience pica during pregnancy which is a craving for non-nutritive substances such as ice, dirt, or cornstarch. Pica is often caused by malnutrition or an iron deficiency. While pica may be common in pregnancy, it does not mean it is safe. Consumption of non-nutritive substances may offset intake of nutrient dense foods. Iron or other mineral supplementation may be recommended to decrease these cravings.

It is clear though that even if those changes exist they depend very much on each individual woman.

A psychological component is also discussed. The cultural idea of eating for 2, or a sense that pregnant women can follow cravings, uninhibited might contribute to following cravings and aversions that are normally not followed.



Food Safety Considerations

Food Safety Prevents Food borne Illness For the Woman and Fetus

During pregnancy, the maternal immune system is suppressed to allow a genetically different fetus to live and grow in her body. This makes the pregnant woman more vulnerable to food borne illnesses. Here is a review of food safety rules the family should always observe. These rules are even more important during pregnancy:


Beyond basic food safety skills, pregnant women are advised to avoid raw mats, fish and dairy. Those raw products carry the risk of four types of pathogens that are harmful to the fetus.


The following pathogens cause only mild flu-like symptoms in pregnant women, but can pass through the placenta and infect the fetus with dire consequences.

Women are advised to avoid eating undercooked meats—no medium rare steaks or burgers, salami for example— and cleaning a cat’s litter box because of increased chance of getting toxoplasmosis. Toxoplasmosis is caused by the parasite, toxoplasma. If a cat eats an infected mouse or raw meat, then the parasite is able to multiply inside their intestines and be excreted into their feces. Inhaling infected cat feces or cat litter can cause someone to contract the parasite. If a pregnant woman is infected later during pregnancy, then it can cause complications such as a stillbirth, seizure, jaundice, or miscarriage.

Coxiella, or commonly known as Q fever, is spread to humans from eating contaminated, undercooked meat (usually sheep, cows, and goats) and dairy products. Contact with infected feces, urine, or inhaling infected dust particles can also cause infection. Coxiella is caused by the bacterium Coxiella burnetii. If a pregnant woman becomes infected, it can cause stillbirth, miscarriage, pre-term delivery, or low birth weight. This tends to be more an issue for pregnant women living on a farm or working in food production.

There are some foods that should be better to avoid entirely throughout pregnancy.  Foods such as raw milk, cheese from raw milk, undercooked meats, and some deli meats (salami, pepperoni) may contain Listeria monocytogenes. If consumed, a serious infection called listeriosis may occur. Listeria can pass the placenta and infect the fetus. Listeriosis can not only cause miscarriage and stillbirth, but also life-threatening infections once the infant is born.

Recently dishes based on raw fish such as sushi, sashimi, cervice and tartare have become popular restaurant items. Raw fish carries a risk of infection with fish-borne parasites. Since this is a recent development, for science that is, research is limited. The available research shows though that parasites can infect that gastrointestinal system and might lead to anemia due to blood loss. Pregnancy anemia is connected to fetal growth restrictions and preterm delivery.

The pregnant woman should only eat well-done meats such as burgers and steaks and forgo raw meat deli such as salami and some hams. The milk in the grocery stores is pasteurized and does not pose a risk. Raw milk is sometimes promoted as an healthier and better option in the media but this is not true. Nutrient composition is not different but drinking raw milk is playing Russian roulette with the health of the fetus. More common are raw-milk cheeses sold in grocery stores. Here reading ingredient lists will allow to decide which cheese to avoid during pregnancy.


Consumption of large fish should be limited in pregnancy, certain fish avoided all together.  The larger the fish the more  methylmercury is accumulated in the meat of the fish. Environmental toxins such as methylmercury accumulate mainly via the aquatic food chain. While small fish have low levels of methyl mercury, medium sized fish eat a lot of small fish, accumulating the methylmercury in their muscle. Larger fish accumulate even more by feeding on those medium sized fish.

Mercury is neuro-, nephro-, and immunotoxic, and the growing fetus is especially vulnerable to the effects of mercury. Damage to the developing neurological system is most likely permanent and can range from mild cognitive impairment to severe brain damage depending on the amount the fetus and infant are exposed to.

Since we usually see fish in neatly package pieces in the grocery store, which types should be avoided?  Swordfish, bluefin tuna and Spanish mackerel should be avoided all together because these fish have the highest methylmercury concentrations. Fish with moderate concentrations such as tuna, salmon, cod and haddock should be limited to 8 – 12 ounces per week. Smaller fish such as sardines are at the bottom of the food chain and contain less methylmercury.

It is a balancing act, however, because women are also recommended to increase their intake of omega-3 fatty acids during pregnancy for optimal development of the fetal nervous system and brain. Fatty fish are one of the best sources for omega-3 fatty acids with the highest bioavailability.

It is best for women to choose fish with a lower mercury content such as sardines, salmon, or cod. The Dietary Guidelines recommend between 8 and 12 ounces per week.

Depending on geographical location, pregnant women may not have easy access to wild-caught salmon nor have a large enough grocery budget to buy fresh fish biweekly.

If women have limited access to fresh fish or are concerned about methylmercury exposure there are other sources of omega-3s such seaweed, flaxseed, chia seeds, and walnuts as well as fortified products such as certain milk varieties.



Alcohol and Excessive Caffeine Intake May Cause Problems During and After Pregnancy

Let’s start with alcohol because here the research is very clear. Women should avoid alcohol while trying to become pregnant and during pregnancy. There is no safe time during pregnancy for alcohol consumption. All types of alcohol are equally harmful.

Alcohol consumption during pregnancy can cause miscarriage, stillbirth, and a range of lifelong physical, behavioral, and intellectual disabilities. Drinking alcohol during the first weeks, when organs and tissues develop, can lead to changes in facial features. The vulnerable, developing neurological system can be impacted in varying degrees at any time during the pregnancy and can lead to long-term memory, attention and behavior problems in the child.  These disabilities are known as fetal alcohol spectrum disorders (FASDs).

On the other hand, caffeine research is not as clear. Naturally, scientists cannot research the effects of caffeine on the human fetus. This would be unethical. The existing research was conducted in mice and results from studies asking mothers about their caffeine consumption, retrospectively, after pregnancy. After consumption, caffeine crosses the placenta and can be found in the umbilical cord blood, fetal blood, and amniotic fluid. In animal studies caffeine seems to reduce the blood flow to the placenta. Based on this research, scientists are concerned about low birthweight newborns and an increased risk for miscarriage when caffeine intake is high.

The scientific evidence is at this point is inconclusive but it seems to be clear that moderate caffeine consumption is not a concern.

Pregnant women should limit the amount of caffeine to less than 200 mg per day. How much in terms of caffeinated drinks is that? It depends what beverage consumed. A brewed coffee house coffee has around 150 mg of caffeine. One cup—small 8 ounce not a big 12 ounce mug—would be enough. One can of energy drink can have 111 mg of caffeine per 12 ounce can. A mug of black tea would be around 75 mg.


Interested in More Information?

Alcohol Use in Pregnancy (CDC): https://www.cdc.gov/ncbddd/fasd/alcohol-use.html


Editor: Gabi Ziegler

NUTR251 Contributors:

  • Spring 2020: Haley Jensen, Hailie Slepicka, Alonda Iturbide, Brittany Southall, Eugene Baraka
  • Fall 2020: Shalin Bhakta



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