In which trimester should pregnant women avoid lying on their back?

In which trimester should pregnant women avoid lying on their back?

• A. First Trimester
• B. Second Trimester
• C. Third Trimester
• D. Any Trimester

Answer: (B)

As pregnancy advances, lying on the back can press the growing uterus against the major blood vessels, especially the inferior vena cava, which reduces venous return to the heart. That drop in return can lower the mother’s blood pressure and decrease oxygen delivery to the fetus. This risk becomes noticeable once the uterus is larger, which is why many guidelines emphasize avoiding the supine position starting in the second trimester. The safest alternative is to lie on the side, preferably the left, to improve blood flow to both mom and baby. So, starting in the second trimester, avoiding lying on the back is the practical recommendation. The first trimester is typically less of a concern, and while the third trimester also benefits from side-lying, the question’s best match among the options is the second trimester.

As pregnancy advances, lying on the back can press the growing uterus against the major blood vessels, especially the inferior vena cava, which reduces venous return to the heart. That drop in return can lower the mother’s blood pressure and decrease oxygen delivery to the fetus. This risk becomes noticeable once the uterus is larger, which is why many guidelines emphasize avoiding the supine position starting in the second trimester. The safest alternative is to lie on the side, preferably the left, to improve blood flow to both mom and baby. So, starting in the second trimester, avoiding lying on the back is the practical recommendation. The first trimester is typically less of a concern, and while the third trimester also benefits from side-lying, the question’s best match among the options is the second trimester.