Alcohol

When you consume alcohol during pregnancy, it passes freely through the placenta to your baby. If you choose to drink alcohol while you are pregnant, you will increase the risk of your baby being born with a Fetal Alcohol Spectrum Disorder (FASD). No amount of alcohol has been deemed safe during pregnancy and should therefore, be avoided.
Raw eggs

Raw eggs can carry harmful organisms such as E Coli and Salmonella during pregnancy as these can infect pregnant woman leading to an intestinal infection. Therefore, it’s best to avoid raw eggs during pregnancy.
Fish rich in mercury

Fish high in mercury such as shark, Swordfish, king Mackerel and tilefish should be avoided during pregnancy. It is highly recommended that pregnant women eat more than 12 ounces of fish per week. If possible limit fist intake to not more than 2 servings per week.
Soft cheese

Try to avoid soft cheese like Feta, Brie and Camembert cheese, blue-veined cheese, queso blanco, queso fresco and Panela. Cheese is safe to eat if it is labelled pasteurized.
Raw meats and seafood including sushi

A pregnant woman's immune system is severely compromised due to the pregnancy which leaves her highly vulnerable to several infections. All uncooked, rare meats and seafood should be avoided due to high risk of listeriosis and salmonella poisoning. Many people won’t feel the symptoms, but whoever eats these foods is at high risk of listeriosis especially during pregnancy. In some cases, listeriosis during pregnancy can lead to preterm labor or even miscarriage.
Unpasteurized milk and juices

Unpasteurized milk and soft cheeses should be avoided during pregnancy. Any dairy product that is not pasteurized holds the potential of listeria contamination. If the label states that the cheese is prepared from pasteurized milk than its safe for consumption during pregnancy, however, if the label is not clear, it is better to avoid it as these may carry certain bacteria that can lead to food borne illnesses.
Raw vegetable sprouts

During pregnancy, raw vegetables sprouts should be avoided because the bacteria can get into the sprouts. Avoid raw sprouts of any kind including alfalfa, clover, radish and mung bean.
Caffeine

Caffeine is a stimulant and a diuretic; it increases the blood pressure and heart rate both of which are not recommended for pregnant women. It also increases the frequency of urination causing reduction in body fluid levels and resulting in dehydration. According to a study women with caffeine intake greater than 200 mg are at increased risk of miscarriage. Caffeine crosses the placenta to the baby. Since the metabolism of is still maturing it won’t be able to handle and metabolize the caffeine.
Liver

This one may not be that hard to avoid because liver contains high levels of vitamin A, which is not recommended in pregnancy. According to some studies, high levels of vitamin A early in pregnancy has been associated with an increased risk of birth defects. It’s best to stay away from it when you are pregnant.
Herbal supplements

Since herbs are not usually rigorously tested like other medications, their safety during pregnancy is not known. For this reason, stick to regular decaffeinated tea and talk to a healthcare provider before continuing herbal supplements during pregnancy.