Dark yellow urine during pregnancy can have various causes, some of which are normal while others may require medical attention. In most cases, it is simply due to dehydration, as pregnant women need more fluids to support the increased blood volume and amniotic fluid. However, it could also be a sign of concentrated urine caused by certain medications or vitamins. If accompanied by other symptoms like pain or discomfort during urination, frequent urination, or fever, it may indicate a urinary tract infection (UTI) which requires prompt treatment. Other potential causes include liver issues or bile duct obstruction. It's best for the pregnant woman to consult her healthcare provider to determine the cause and receive appropriate guidance. Drinking plenty of water throughout the day can help alleviate dehydration-related dark yellow urine.