Mothers need to take in additional calories during pregnancy for natural weight gain. However, the extra calorie that are needed are not as high as most mothers think. Pregnant women only need to add about 100kcal for the first trimester, and add another 200kcal for the second and third trimester. A cup of soy milk supplies you with your excess calorie needs for the first trimester, and a medium-sized banana, an apple or a cup of soy milk with a piece of digestive biscuit provides you with the extra nutrients needed during second and third trimester.