Pregnant women generally follow a diet pregnancy dictates. Their levels of vitamins and minerals in their blood required for the health of the baby decline. These prenatal vitamins include iron (for blood), calcium (for bones), and folic acid supplementation during the early weeks of pregnancy to protect against certain birth defects of the spine and brain.

There are also certain foods that should be avoided in the diet pregnancy requires. Fish such as shark, swordfish and mackerel should be excluded because they have high levels of mercury, which in high doses can be dangerous to a baby's developing nerve system. For the same reason, pregnant women should limit their pregnancy nutrition to no more than six ounce of white tuna per week. Caffeine should be limited as it can cause irritability, nervousness, and insomnia.

Hence, the diet pregnancy demands usually includes heavy dosages of prenatal vitamins and iron supplements. While it is recommended to follow an increase in vitamin intake, one should be careful to avoid overdosing. In general, water soluble vitamins such as B,C,D and folic acid are excreted in the kidneys so the excess amounts of these vitamins are usually urinated out. However, fat soluble vitamins, A, E, and K are stored in body tissue and fat and can accumulate to toxic levels. Excess amounts of Vit A (10,000 IU per day) have been associated with an increased risk of fetal malformations.

Only the requirements for iron, folic acid and Vitamin D double during pregnancy. The recommended daily allowances for calcium and phosphorus increase by only a half. For pyridoxine and thiamine, the RDA increase is about one third, and for all other nutrients except vitamin A the increase is by less than 20%. For vitamin A there is no increase necessary. Mega doses of any vitamins are neither necessary nor recommended in pregnancy.

Besides the prescribed prenatal vitamin course, sensible pregnancy nutrition has to be observed by the woman to remain healthy while pregnant and to ensure the birth of a healthy baby. The traditional diet pregnancy "do's" and "don'ts" such as having regular exercise, controlled dietary habits, staying away from junk food, alcohol and caffeine, including staying away from excessive dietary fat are usually good advice.

Contrary to common belief, it isn't how much one eats that's so important (in fact, a pregnant mom needs to increase her calorie intake only by 300 calories a day during the second and third trimester), but what one eats. This is important because what the woman eats plays a vital role in determining the health of the little one she is so anxiously awaiting for. The diet should be nutritious with a moderate fat content including lots of whole grains, fruits and vegetables, moderate amounts of lean protein. The weight gain for a normal pregnancy would be about 25 pounds, most of which you gain during the third semester. For underweight moms a good pregnancy diet would bring about an increase in weight of at least 28 to 40 pounds.