Final answer:
During the second and third trimesters of pregnancy, the recommended weight gain is approximately 1 pound per week, supported by an additional caloric intake of around 300 calories per day.
Step-by-step explanation:
During the second and third trimesters, pregnant women should gain approximately 1 pound per week. This weight gain is important for the healthy development of the fetus as well as to accommodate changes in the mother's body, such as increased blood volume and the development of additional breast tissue. It's also interesting to note that during this period, only about 300 extra calories per day are needed to support these changes.
The fetus experiences rapid growth during this time, especially in the third trimester, when it grows to approximately 3 to 4 kg (6.5-8.5 lbs.) and reaches about 50 cm (19-20 inches) in length. Notably, excessive weight gain can be detrimental to both the mother and the baby, highlighting the importance of a well-balanced increase in weight.
Contributors to Weight Gain During Pregnancy
Weight gain during pregnancy results from the growing fetus, enlarged uterus, increased amniotic fluid, placenta, additional breast tissue, and an increased blood volume. Furthermore, a small reserve of fat is stored to meet the metabolic demands of breastfeeding after delivery, contributing to approximately 2.3 kg (5 lbs) of the total weight gained in a normal pregnancy.