Hello, Edema or swelling during the third trimester occurs due to the body retaining excessive fluid in the ankles and feet due to changes in the blood chemistry and increased pressure in the pelvis veins due to the growing fetus, excessive amniotic fluid can also be a reason. After delivery, the swelling generally goes away on its own. Keep your foot on a pillow while in bed or a stool when seated. Restrict salt intake, take iron and calcium supplements. If the edema remains get Thyroid function tests done, get treated. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician