My sister just had her prenatal check-up a week ago. She is on her 5th month and her doctor was wondering on why she was not gaining weight. She was 69 kilograms a month before the visit and now she weighs 65kilograms. Her doctor prescribed vitamins and advised her to consume milk everyday since the first trimester. Why is it that she is not gaining weight? She even lost weight. Considering the fact that she is on her second trimester of pregnancy.