Nutrition is an important factor for a healthy pregnancy. During pregnancy, nutrient needs are increased, and some foods or substances may have a negative effect on the health of the pregnant woman and her baby. 

In this article, we will focus on the foods or ingredients that should be avoided during pregnancy. 

Foods that may be harmful: 

The pregnant woman and the foetus are at higher risk from foodborne infections caused by eating contaminated foods, such as toxoplasmosis, salmonellosis and listeriosis.1 These infections can lead to pregnancy complications such as premature delivery or even miscarriage, and can affect the foetus, even if the pregnant woman is unaffected.1,2 

In this case the foods that should be avoided are: 
  • Ready to eat salads or salads from restaurants (unless they are from a place where you know they are well washed) 
  • Raw vegetable sprouts such as clover and radishes 
  • Ready-made fruit salads 
  • Unpasteurised juices 
  • Unpasteurised cheeses such as: roquefort, brie, unpacked feta and camembert. These can be eaten when they are very well cooked. 
  • Raw or undercooked meats and poultry. 
  • Raw fish such as sushi or sashimi and cold smoked fish such as salmon 
  • Raw or undercooked eggs or foods likely to contain raw eggs such as: tiramisu and homemade ice cream 
  • Cold precooked meats. Warm to a temperature above 75°C before eating 

In addition to avoid foodborne infections, it is important to maintain good hand washing before and after handling food and to keep the area and utensils used to prepare food clean. Extra care is needed when preparing raw foods such as meat.2  

Fish rich in mercury 

Eating fish is essential for the physical and nervous system development of the foetus and to prevent complications during pregnancy, thanks to its rich content of omega-3 fatty acids and other nutrients such as minerals, vitamins and high-quality proteins.3,4  However, fish with high concentrations of mercury can be harmful to your baby. Such fish includes shark, king mackerel, swordfish and white (albacore) tuna. 
You can safely consume a variety of fish that are low in mercury such as: salmon, sardines, anchovies and cod. It is recommended to consume 2-3 portions of fish per week, corresponding to 280-360g of fish. 
The US Food and Drug Administration (FDA) and the European Environmental Protection Agency (EPA) provide authoritative information on fish species and their safety.3,4,5   

Excessive caffeine intake 

Excessive caffeine intake can affect the birth weight of the newborn. Its consumption should not exceed 200mg per day, which is equivalent to around 2 cups (240ml per cup) of coffee per day. Within these daily recommendations, other sources of caffeine such as chocolate, cocoa, tea and cola drinks should also be considered.6 

Alcohol 

Drinking alcohol can cause complications in pregnancy and affect the development of the foetus. It can also cause a wide range of disorders known as foetal alcohol spectrum disorders (FASD), including foetal alcohol syndrome (FAS). As it is unclear whether small amounts are safe and since each woman has different sensitivities to alcohol, zero consumption is recommended.7.8,9  

Herbs 

Many women consider it safe to consume herbs since they are natural. However, research data regarding their safety is limited and many herbs contain substances that are not recommended during pregnancy. The safety of some herbs also depends on how they are used. Rosemary and garlic, for example, are considered safe when used in food, but are likely to be unsafe when used in higher concentrations in supplement form.10 Many herbs may also interact with medication the pregnant woman may be taking, resulting in negative consequences for her and the baby.11  
Some of the herbs that are considered safe in pregnancy are: mint leaves, red raspberry leaves and ginger. However, before any herb consumption, it is important to consult a specialist. 10,11  

Soy 

Soybeans are rich in phytoestrogens, substances that occur naturally in plants. However, because soy can affect normal oestrogen levels, during pregnancy it is recommended to limit the consumption of soy and soy-based products (e.g., tofu cheese, soy milk).8 

Additional sugars 

Increased consumption of sugar may contribute to the development of gestational diabetes, pre-eclampsia and increased weight gain. Some of the foods that contain added sugars are sweets, ready-made cakes, carbonated drinks, cereal bars and chocolate. In contrast, foods such as fresh or dried fruits, vegetables and whole grain foods reduce the risk of the above complications due to their high fibre content. 

Artificial sweeteners 

Although the use of artificial sweeteners (aspartame, sucrose and stevia) doesn’t appear to cause any toxicity in humans, due to the need for more research, it is advisable to consume them in moderation.12  

Saturated and trans fatty acids 

Increased consumption of saturated and trans fatty acids can contribute to increased levels of bad cholesterol (LDL) in the blood, affecting vascular health and heart health. 13,14  In pregnancy, a normal increase in these levels may occur due to changes in the pregnant woman’s body. 
However, it is important to continue to limit your consumption of these fats.15  Such fats are found in foods such as butter, fried foods, high-fat meat, ready-made cereal bars and biscuits. 
Replace the above fats with good quality fats such as olive oil, unsalted nuts, tahini, and avocado.14 

Increased intake of vitamin A 

Vitamin A is essential for the health of the pregnant woman and the foetus. Like several other nutrients, the need for this vitamin is increased during pregnancy. When taken in proper amounts it contributes to proper growth, good vision, bone health and the various organs of the foetus. However, in excessive doses it can become toxic and have a teratogenic effect towards the foetus so dietary sources, as well as supplements that have increased concentrations of vitamin A should be avoided. Vitamin A intake should not exceed 10000 IU per day after 60 days of conception. Liver is also a rich source of vitamin A so its avoidance in pregnancy is recommended.16 

References 

1. Position of the American Dietetic Association: Nutrition and Lifestyle for a Healthy Pregnancy Outcome. (2008). J Am Diet Assoc. 108, p553-561.
2. Foodsafety.com. (2019). Available at: https://www.foodsafety.gov/people-at-risk/pregnant-women {Accessed 2 September 2020}
3. De Seymour, J. V., Simmonds, L. A., Gould, J., Makrides, M., & Middleton, P. (2019). Omega-3 fatty acids to prevent preterm birth: Australian pregnant women’s preterm birth awareness and intentions to increase omega-3 fatty acid intake. Nutrition Journal, 18 (1).
4. Kominiarek, M. A., & Rajan, P. (2016). Nutrition Recommendations in Pregnancy and Lactation. Medical Clinics of North America, 100 (6), p1199–1215.
5. Administration USFaD. (2020). Advice about Eating Fish. Available at: https://www.fda.gov/food/consumers/advice-about-eating-fish {Accessed 2 September 2020}
6. Peacock, A., Hutchinson, D., Wilson, J., McCormack, C., Bruno, R., Olsson, C., Mattick, R. (2018). Adherence to the Caffeine Intake Guideline during Pregnancy and Birth Outcomes: A Prospective Cohort Study. Nutrients, 10(3), 319.
7. Lisa Schölin. (2016). Prevention of harm caused by alcohol exposure in pregnancy. World Health Organization
8. The Institute of Preventive, Environmental and Occupational Medicine, Prolepsis (2014). National Nutrition Guide for Women, Pregnant and Lactating Women. Athens: Institute of Preventive, Environmental and Occupational Medicine, Prolepsis
9. Cyprus Addictions Authority (2018). Clinical Guidelines for the Prevention, Diagnosis, and Treatment of Fetal Alcohol Spectrum Disorder and Fetal Alcohol Syndrome. Cyprus: Addiction Treatment Authority
10. American Pregnancy Association. (2017). Herbs and Pregnancy. Available at: https://americanpregnancy.org/is-it-safe/herbs-and-pregnancy-1003 {Accessed 2 September 2020}
11. Illamola, S. M., Amaeze, O. U., Krepkova, L. V., Birnbaum, A. K., Karanam, A., Job, K. M., Enioutina, E. Y. (2020). Use of Herbal Medicine by Pregnant Women: What Physicians Need to Know. Frontiers in Pharmacology, 10.
12. Goran, M. I., Plows, J. F., & Ventura, E. E. (2018). Effects of consuming sugars and alternative sweeteners during pregnancy on maternal and child health: evidence for a secondhand sugar effect. Proceedings of the Nutrition Society, 1–10.
13. American Heart Association. (2017). What is Cholesterol? Διαθέσιμο στο: https://www.heart.org/en/health-topics/cholesterol/about-cholesterol {Accessed 21 September 2020}
14. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. (2005). Your Guide Lowering Your Cholesterol With TLC.
15. Bartels, Ä., & O’Donoghue, K. (2011). Cholesterol in pregnancy: a review of knowns and unknowns. Obstetric Medicine, 4(4), p147–151.
16. Bastos Maia, S., Rolland Souza, A., Costa Caminha, M., Lins da Silva, S., Callou Cruz, R., Carvalho dos Santos, C., & Batista Filho, M. (2019). Vitamin A and Pregnancy: A Narrative Review. Nutrients, 11(3), 681.