In general, pregnant women need between 2,200 calories and 2,900 calories a day. A gradual increase of calories as the baby grows is the best bet. Here is an overview of how calorie needs change during each trimester:
The first trimester does not require any extra calories.
During the second trimester an additional 340 calories a day are recommended.
For the third trimester the recommendation is 450 calories more a day than when you are not pregnant
Avoid extra calories by cutting down on foods high in fat and added sugars. Replace regular soda, sweets and fried foods with healthy options like low-fat milk and yogurt, whole fruit and whole grains.