What should you know about unilateral leg swelling in pregnancy?

Pregnancy can cause fluid retention and pressure on veins, often making both ankles or feet look swollen, especially later in the day. Swelling that is clearly greater on one side, starts suddenly, or comes with warmth, redness, tenderness, or a heavy ache is different. These features can occur with deep vein thrombosis, a clot in a deep vein of the leg. A clinician may need to examine the leg and arrange an ultrasound. Swelling with a severe headache, vision changes, pain under the ribs, or sudden swelling of the face and hands also deserves urgent review because these symptoms can occur with pre-eclampsia.

Contact your maternity team, obstetrician, or urgent medical service today for advice about new one-sided swelling. Keep the leg comfortable while you arrange care, and avoid massaging a painful or swollen area. Do not start, stop, or borrow blood-thinning medicine. Tell the clinician when the swelling began, whether it is worsening, and whether you have pain, redness, breathlessness, chest discomfort, headache, or visual symptoms.

Call emergency services immediately for sudden shortness of breath, chest pain, coughing blood, fainting, or severe weakness. Seek urgent maternity assessment for rapidly increasing one-sided swelling, significant calf or thigh pain, a hot or red leg, severe headache, flashing lights or blurred vision, or pain beneath the ribs. These warning signs need assessment even if the swelling itself seems manageable.

Ask: Could this be a clot, and do I need a leg ultrasound? Which symptoms should send me to emergency care? How can I stay mobile safely while waiting for assessment? Could my blood pressure or urine need checking for pre-eclampsia?