What happens to the baby's weight and size by the end of the pregnancy?

By the end of pregnancy, a typical baby is born at an average weight of around 7-8 pounds, which is why this answer is accurate. During the course of pregnancy, particularly in the third trimester, the baby undergoes significant growth not just in weight but also in overall size. By the end of gestation, healthy weight ranges indicate that a baby often reaches this average, reflecting a normal developmental process.

In contrast, the other options do not represent the typical outcome of fetal growth. The scenario where the baby stays the same size does not reflect the natural growth progression that occurs throughout pregnancy. Similarly, the idea that the baby decreases in size contradicts what typically happens as the fetus develops and matures. The notion that the baby doubles in size lacks accuracy because while a baby does gain weight, it does not double from a smaller amount to reach 7-8 pounds; rather, it follows a steady growth pattern throughout gestation. Thus, the correct response captures the expected outcome for a healthy newborn.