First Trimester

• Many women may find their appetites changes very early in the first trimester of pregnancy---possibly even before they know that they are pregnant. Some women may suddenly find themselves not hungry at all, and that even the mere thought of food makes them feel ill. This kind of appetite change usually accompanies morning sickness and once that passes, so does the aversion to food. In most cases, you shouldn't worry too much if you can't eat much during the first trimester: according to KidsHealth.com, the baby will get most of the nutrients that you do ingest, so rarely does fetal harm result from eating less than normal. Nevertheless, even if you're not hungry, you should try to eat small portions of healthy food when you can handle it, and not give in to the desire to abstain.
  
  

Second Trimester

• The second trimester of pregnancy often can bring a huge increase in appetite. It may seem as if no matter how much you eat, you can never get enough. According to What To Expect.com, this insatiable demand is caused by your growing baby and its need for extra nourishment. If you are constantly feeling hungry at this stage, you should give into your body's desires---but make sure that the foods you consume are healthy ones. Try to fill up on healthy treats like fruits and whole grains. Also, don't try to stick to the usual three meals a day program: Have five or six small meals a day to help keep your appetite under control and prevent binge eating.
  
  

Third Trimester

• A pregnant woman in her third trimester may once again feel a lack of appetite. Family Education.com states that this is often because the fetus has now grown so large that it is putting pressure on your abdomen, and there is less room for food. However, some women have just the opposite change in appetite: An enormous urge to eat. According to babiesonline.com, this is probably because the baby gains weight at an extraordinary rate during the third trimester, and the mom-to-be's body is trying to keep pace with the growing baby's needs.
  
  

Any Trimester

• Cravings for certain foods can strike at any point during pregnancy. No one knows for sure why cravings occur. According to Parents.com, some experts believe that it is the body's way of telling a pregnant woman that she is lacking certain nutrients. For example, a craving for meat might mean than your body needs protein, or a desperate taste for oranges might mean your body needs vitamin C. However, according to Baby Center, other experts doubt that this theory explains all cravings given pregnant women often crave unhealthy foods as well as healthy ones.