What occurs during the second trimester of pregnancy?

What occurs during the second trimester of pregnancy?

• A. Zygote implants into the endometrium
• B. The placenta forms new blood cells
• C. Growth of the fetus
• D. Labor begins

Answer: (C)

During the second trimester, the key process is rapid growth and maturation of the fetus. After the foundations of development are laid in the first trimester, weeks about 13 to 27 involve substantial increases in size and refinement of organ systems, moving the fetus toward viability. The placenta continues to support this growth through nutrient and gas exchange, but the main production of blood cells isn’t its primary role in this period. Fetal blood formation happens mainly in the liver and spleen early on and then shifts to the bone marrow later. Zygote implantation occurs earlier in pregnancy, and labor begins near the end of gestation, not in the second trimester. So the growth of the fetus best reflects what happens during this stage.

During the second trimester, the key process is rapid growth and maturation of the fetus. After the foundations of development are laid in the first trimester, weeks about 13 to 27 involve substantial increases in size and refinement of organ systems, moving the fetus toward viability. The placenta continues to support this growth through nutrient and gas exchange, but the main production of blood cells isn’t its primary role in this period. Fetal blood formation happens mainly in the liver and spleen early on and then shifts to the bone marrow later. Zygote implantation occurs earlier in pregnancy, and labor begins near the end of gestation, not in the second trimester. So the growth of the fetus best reflects what happens during this stage.