There are many causes of leg and foot swelling in women in their 30s, such as nephrotic syndrome, heart failure and cirrhosis, and lower extremity venous thrombosis. 1. Nephrotic syndrome: patients with nephrotic syndrome can be caused by a large amount of proteinuria leading to hypoproteinemia, causing a decrease in plasma colloid osmotic pressure, so that water seeps from the blood vessels inside and outside the tissue interstitial space, thus resulting in the phenomenon of swollen legs and feet. 2. Right heart failure: when right heart failure leads to blood stasis in the body circulation, the venous pressure in the body circulation rises, and the blood in the venous vessels of the lower limbs extravasates into the tissue space, resulting in the phenomenon of leg and foot swelling. 3. Liver cirrhosis: when the ability of liver to synthesize albumin decreases in liver cirrhosis and hypoproteinemia occurs, plasma colloid osmotic pressure decreases and water seeps out of the blood vessels into the tissue interstitial space, resulting in swelling of legs and feet. 4. Lower extremity venous thrombosis: If the patient has lower extremity venous thrombosis, the obstruction of reflux will also have edema of the feet, and can be accompanied by pain, numbness and other symptoms. There are many other reasons that can lead to the occurrence of swollen legs and feet in women in their 30s, it is recommended to go to a regular hospital, consult with a professional doctor, cooperate with the doctor to complete the relevant examination, and clarify the cause of treatment.