For pregnant women, blood volume gradually increases from 6 weeks after pregnancy, reaches a peak at 34 weeks, and remains at this level until two weeks after delivery before returning to pre-pregnancy levels. Blood volume can increase by about 40% compared to non-pregnancy, so when blood volume increases, interstitial fluid will also increase. Because when blood increases, the increase in plasma is greater than the increase in blood cells, etc., so the blood components will be relatively diluted, and the relative concentration of plasma albumin will be lower than during non-pregnancy. Plasma albumin is the main component that maintains plasma osmotic pressure. Plasma osmolality is lower during pregnancy than during non-pregnancy. This allows water in the bloodstream to easily penetrate into the interstitial fluid, causing edema of the lower limbs. 200 Examples of Nutritional Recipes for Pregnant Women in Three Months in Ultra-clear, Full-Color PDF. At the same time, the uterus increases after pregnancy, which increases the pressure in the pelvis, thus affecting the venous blood flow of the lower limbs. This is also one of the important causes of lower limb edema. If the edema during pregnancy becomes lighter after rest or sleep, it is physiological and there is no need to worry. Therefore, as long as the blood pressure is not high and the kidney function is normal, swelling of the legs and feet at 37 weeks of pregnancy is normal and expectant mothers do not need to worry. Swollen feet in pregnant women may be caused by increased water content in the body during pregnancy, poor blood circulation and other reasons. Here are some tips for relieving swollen feet: Get plenty of rest and avoid standing, sitting, and walking for long periods of time. Wear loose, breathable, comfortable shoes and avoid high heels and tight clothing. Elevate your feet, either using a pillow or sitting on a high cushion to prop them up. To massage your feet, you can soak your feet in warm water or use a foot massager. Limit salt intake and control the accumulation of water in the body. Increasing the intake of foods containing potassium, such as bananas, potatoes, etc., can help control water balance. If necessary, you can consult a doctor and use appropriate medications under the guidance of your doctor. It should be noted that if the swollen feet are accompanied by other uncomfortable symptoms, such as headache, blurred vision, etc., you need to seek medical treatment in time.