Final answer:
Venous congestion of the legs commonly occurs in the 3rd trimester of pregnancy, due to the compression of pelvic blood vessels by the growing fetus and uterus, causing circulatory problems like varicose veins.
Step-by-step explanation:
During which trimester does venous congestion of the legs commonly occur in pregnancy? The correct answer is c) 3rd trimester. This is the time when the uterus expands rapidly, taking up a significant portion of the woman's abdomen, and the fetus's growth is most significant. As the fetus and the uterus grow, they can compress underlying pelvic blood vessels, impeding venous return from the legs and pelvic region. This compression can cause circulatory problems such as varicose veins or even clots due to the pressure on returning veins as they enter the abdominal cavity.
During the third trimester, a pregnant person may also experience more frequent urination, swelling of the lower extremities, and back pain. The increased blood volume and moderate rise in pulse and blood pressure during pregnancy further contribute to these circulatory changes and challenges.