The pregnant mother in her first trimester of pregnancy needs to maintain a healthy diet, thus giving her baby a good start. Gaining insufficient weight denies the baby needed calories while gaining too much puts mother and baby at risk.
The expectant mother needs to eat nutritious foods and make sure she's taking in enough calories to support her needs and those of her unborn child. During the first trimester, she doesn't need to increase her daily caloric intake, according to PubMedCentral.
The unborn baby and mother gain a healthy amount of weight when the mother eats a healthy number of calories in her first trimester as she did before she became pregnant. The quality of food she eats is more important than increasing the quantity of calories, according to Mama's Health.
The fetus benefits from healthy foods taken from every food group. If the mother doesn't take in between 1,600 to 2,200 calories during her first trimester, it becomes harder for the baby to grow to a healthy weight, according to Mama's Health.
While in the first trimester, the mother doesn't need to add any calories, in the second and third trimesters, she should eat about 1,900 to 2,500 calories a day. If she is underweight, she should gain 27 to 40 lb. during her pregnancy. If overweight, she should gain 15 to 25 lb.; if obese, she should gain up to 15 pounds. If a woman is in a normal weight range, she should gain 25 to 35 lb. during her pregnancy.
Along with taking in a healthy number of calories, the mother needs to eat foods high in folates such as spinach, orange juice, broccoli, breakfast cereals and beans. She should also eat high-fiber foods, vegetables and fruits.