Prenatal vitamins are vitamin and mineral supplements that you'll likely be prescribed by your obstetrician if you're pregnant. The vitamins and minerals help provide for your increased nutrient needs during pregnancy. While they can cause some digestive side effects, they can't make you hungry--though pregnancy certainly can.
Prenatal Vitamins
During pregnancy, your body provides all the nutrients to your developing fetus. This includes both macronutrients--the energy-providing molecules you obtain from carbohydrates, proteins and fats--and micronutrients, which are vitamins and minerals. Though you can try to meet all your nutrient needs through food alone, it's sometimes difficult, which is why your obstetrician may prescribe a prenatal vitamin or recommend that you purchase one over-the-counter.
Prenatal Components
Prenatals are actually very similar to the regular women's daily multivitamin and mineral supplements that you might have taken before pregnancy. The difference is primarily that they contain more iron and more folic acid than traditional women's vitamins. Iron helps you produce more red blood cells, which help deliver oxygen to your fetus, explain Drs. Michael Roizen and Mehmet Oz in their book "You: Having A Baby." Folic acid assists in nervous system development.
Pregancy and Hunger
During pregnancy, you may feel more hungry than you usually do, particularly once you're through the first trimester. Though you might be taking prenatal vitamins, the vitamins don't actually have anything to do with the hunger. In fact, many women notice that prenatal vitamins cause stomach upset and decrease their appetite, explain Heidi Murkoff and Sharon Mazel in their book "What To Expect When You're Expecting." Pregnancy hunger is purely a result of your growing baby and increased caloric needs.
Weight Gain
As long as you're not so hungry and eating so much that you're gaining an unhealthy amount of weight, pregnancy hunger is both normal and completely healthy. Drs. Roizen and Oz point out that women who were at a healthy pre-pregnancy weight will typically need to gain 25 to 35 pounds during pregnancy, which typically results from an increased caloric intake of about 300 calories per day. Your obstetrician will help you monitor your weight.