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Why do pregnant people have to avoid certain foods?

  • Apr 8
  • 4 min read
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Overview

Being pregnant is obviously a huge lifestyle change, and one of the most obvious ways this shift shows up is in your diet. Although pregnancy comes with increased appetite and new food cravings, it is also recommended to avoid certain foods for the health of yourself and your baby. The reasons to avoid particular foods come from both specific effects and a generalized increased risk of food-borne infections. Read on to learn which foods fall into each category!


Why do pregnant people have to avoid certain foods?

There are two main reasons that pregnant women should avoid consuming certain foods. The first is that the food may contain particular factors that specifically affect the development of the baby. The second is that, since the immune system is altered during pregnancy, pregnant women have a harder time fighting off infections. For this reason, pregnant women may want to avoid foods that don’t have any particular effect on the baby but are more likely to be contaminated with harmful bacteria and toxins.


Both categories of food are described in further detail below.


What foods specifically affect the growing baby?

The first category of food to avoid during pregnancy are foods that have a particular factor that can affect the growing baby. These factors include:

  • Excess levels of vitamin A: Foods with high levels of vitamin A include liver and liver products. Too much vitamin A can interfere with genes essential for fetal development, leading to nervous system or cardiovascular system abnormalities.

  • Mercury: Tuna, swordfish, and other high-mercury fish are not recommended during pregnancy. Mercury can damage an unborn baby’s nervous system, leading to hearing and vision problems.

  • Caffeine: Although the reason for the effects is not fully understood, caffeine has been shown to lead to increased pregnancy complications, such as low birthweight or miscarriage. Pregnant women metabolize caffeine up to six times more slowly than non-pregnant women, and caffeine passes to the fetus, who may not have the enzymes needed to metabolize the caffeine itself. For this reason, excess caffeine should be avoided, although up to 200 mg per day is still considered safe.

  • Herbal teas: The ingredients of herbal teas vary and may have a number of poorly understood effects and unknown levels of caffeine. It is therefore recommended to avoid herbal tea during pregnancy.

  • Alcohol: Consumption of alcohol during pregnancy can lead to a number of complications, including miscarriage, stillbirth, and fetal alcohol syndrome (which causes additional long-term health issues). Alcohol passes from the mother to the unborn baby (or to breastfeeding babies) and can affect development. Not all babies are equally as affected by alcohol, but since it’s impossible to know which ones will be, it’s best to avoid alcohol entirely while pregnant and breastfeeding.


What foods are more likely to contain harmful germs?

Unwashed and undercooked foods are more likely to be contaminated by bacteria, viruses, or toxins than washed and cooked food. Although anyone is at risk of developing a food-borne illness, pregnant women are more susceptible. Listeriosis, the infection caused by Listeria bacteria is particularly harmful to pregnant women and can result in miscarriage, stillbirth, or premature delivery. Due to their altered immune system, pregnant women are 10 times more likely to develop listeriosis than non-pregnant people.


The following foods have a higher risk of causing food-borne illness and should be avoided as much as possible during pregnancy. However, since bacteria are killed by heat, heating any of these foods to an appropriate temperature (varies by food, so look it up for what you’re preparing) will make the food safer to eat.

  • Mold-ripened soft cheese with a white coating (such as brie, camembert, or chèvre) and blue cheese

  • Raw or undercooked meat or poultry

  • Hot dogs and lunch meats

  • Smoked or cured fish

  • Raw fish and shellfish

  • Undercooked eggs

  • Raw or undercooked sprouts

  • Unwashed fruits and vegetables

  • Unpasteurized milk and dairy products


Summary

All of the foods on these lists present an increased risk of illness or complications during pregnancy. This does not mean that a single serving of these foods will cause untold harm to an unborn baby, but many mothers choose to play it safe and avoid these riskier foods entirely. If you have particular concerns, discuss your diet with your doctor, to better understand what is right for you.


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