Final answer:
During the second and third trimesters, a pregnant person needs an additional 300 calories per day. This supports the growing fetus and helps ensure adequate weight gain of approximately 0.45 kg (1 lb) per week. The growing fetus's additional weight, increased maternal blood volume, and preparation for breastfeeding contribute to the mother's overall weight gain.
Step-by-step explanation:
Nutritional Needs During Second and Third Trimesters of Pregnancy
During the second and third trimesters of pregnancy, nutritional needs for the mother increase significantly. It is essential for the mother to consume an additional 300 calories per day to support the growing fetus. These additional calories should come from nutritious foods to provide extra proteins, lipids, as well as an increased intake of vitamins and minerals. Weight gain is expected to be around 0.45 kg (1 lb) per week as the fetus grows. The increase in weight also comes from the enlarged uterus, amniotic fluid, and an increase in maternal blood volume. It is also a time when the pregnant person's body is preparing for the demands of breastfeeding.
During the second trimester, typically occurring between weeks 13 to 28, the pregnant person may start to feel more energized, and symptoms like nausea and vomiting may subside. This is also the period when the fetus's movements can be felt, and weight gain becomes more noticeable.
The third trimester spans from weeks 29 to birth, where the uterus expands significantly, leading to rapid weight gain and more pronounced fetal movements. In this trimester, the pregnant person might experience back pain, swelling, varicose veins, and heartburn due to the increased size and weight of the uterus and fetus.