When you're pregnant, concerns over food additives and chemicals take on new significance. You weigh everything that you ingest against its potential risk to your developing baby. Sulfites -- preservatives used in many processed foods as well as wine -- can cause allergic reactions in some people but haven't been proven harmful in pregnancy.
Several different chemical compounds used in food production fall into the category of sulfites. Sulfur dioxide, sodium sulfite, sodium bisulfite, potassium bisulfite, potassium metabisulfite and sodium metabisulfite are all classified as sulfites. Sulfites keep meats, fruits and vegetables from turning brown when exposed to air, which is why they were commonly used on salad bars to keep foods looking fresh. In processed foods, sulfites act as preservatives and bleaching agents. Fermentation in beer and wine also produces sulfites. Sulfites can longer be used on fruits, meats and vegetables, except for potatoes. Foods containing more than 10 parts per million must be labeled as containing sulfites.
Foods containing sulfites don't carry warning labels for pregnant women. Alcoholic beverages carry warning labels for pregnancy because the alcohol content can cause birth defects, not because the sulfites pose a risk in pregnancy.
The U. S. Food and Drug Administration estimates that around 1 percent of Americans has a sulfite sensitivity. If you have a sulfite sensitivity, you may develop symptoms such as wheezing, trouble breathing, chest tightness, hives, facial swelling known as angioedema, vomiting and diarrhea. Between 5 and 10 percent of people with asthma may have sulfite sensitivity, although numbers vary, reports the Cleveland Clinic.
If you're pregnant and have a sulfite sensitivity, a reaction that causes difficulty breathing could affect the amount of oxygen that your baby receives through the placenta. Read labels carefully to avoid sulfites if you have ever had a sensitivity reaction. If you have asthma, eat foods high in sulfites cautiously, since having asthma increases your risk of developing sulfite sensitivity. Sulfite sensitivity can appear at any age, even if you've consumed sulfites before without a problem.