Nutrients from the foods you eat become the building blocks that form the organ systems, brain, skeleton, muscles, and all the components that make up your baby. Therefore, what you eat can be one of the most important factors in determining your baby’s future health. The mother's diet during her pregnancy can determine the child's brain size and birth weight; if the mother does not provide enough nutrients to the child while he/she is in utero, his/her brain will not develop to its full potential. In order for the child to get enough nourishment during the pregnancy, the mother should gain an additional 20 percent from her ideal pre-pregnancy weight.
Energy Needs during Pregnancy:
You should not actually “eat for two,” or double your calorie intake. However, in order to gain weight, you do need to eat extra calories. Energy needs for pregnant adult women typically range from 2500–2700 calories/day, but may be more or less depending on factors such as pre-pregnancy weight, height, age, and activity level.
No additional calories are needed during the 1st trimester since the size of the baby is still very small, and recommended weight gain is minimal. However, you should eat an extra 340 calories/day during the 2nd trimester and an extra 450 calories/day during the 3rd trimester to provide much-needed energy for your rapidly growing baby.