Final answer:
During the first trimester, a pregnant person does not need to consume additional calories, but weight gain of approximately 1 lb per month is common. During the second and third trimesters, an extra 300 calories per day are recommended for the growing fetus, resulting in a weight gain of about 1 lb per week.
Step-by-step explanation:
During the first trimester, a pregnant person does not need to consume additional calories to maintain a healthy pregnancy. However, a weight gain of approximately 0.45 kg (1 lb) per month is common. During the second and third trimesters, the appetite increases, but it is only necessary to consume an additional 300 calories per day to support the growing fetus. Most pregnant people gain approximately 0.45 kg (1 lb) per week.